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 Purpose

This guidance is not statutory, it is designed to help contextualise the criteria so that broadly the interpretation is consistent with the general level 1 descriptions in the Qualifications and Credit Framework. These are referenced to the European Qualifications framework at Level 2. Getting the level about right is what we are about NOT prescribing specific contexts or learning methods. That is left to you as a professional teacher.

General Level Descriptor for Level 1

Achievement at level 1 reflects the ability to use relevant knowledge, skills and procedures to complete routine tasks. It includes responsibility for completing tasks and procedures subject to direction or guidance.

Level 1 Knowledge and understanding

  • Use knowledge of facts, procedures and ideas to complete well-defined, routine tasks.
  • Be aware of information relevant to the area of study or work.

 

Level 1 Application and action

  • Complete well-defined routine tasks. Use relevant skills and procedures.
  • Select and use relevant information. Identify whether actions have been effective

 

Level 1 Autonomy and accountability

  • Take responsibility for completing tasks and procedures subject to direction or guidance as needed. 

 

Expansion and examples to illustrate the criteria

 

Unit 1 Computer Science

1. Design, use and evaluate computational abstractions

 

1.1 I can develop abstractions to represent physical objects

Candidates should be able to develop simple abstractions related to physical objects

Evidence: from assessor observations, content of learner portfolios.

Additional information and guidance for assessors:

  • Abstraction is used to reduce complexity. Drawing a circle to represent a wheel is an abstraction of the wheel and represents the possibility to describe many different wheels. Once we have the basic abstraction we can add further information to get different kinds of wheel. eg a big or small wheel, a spoked wheel or a tyred wheel.
  • Candidates should be provided with many opportunities to take physical objects and create abstractions by eliminating the details associated with the main attribute being abstracted. This does NOT require a computer (although there is no ban!) Shapes such as a square to represent a box, a sphere to represent a ball, planet, or star are some of the simplest abstractions. Suitable activities could be to get candidates to use simple shapes to represent familiar objects. eg 3 equilateral triangles to represent a Christmas Tree. Work in pairs. One draws an object the other has to guess what it is and provide instructions to the first to add more shapes to it to make it easier to decide what the original object was intended to represent.
  • In some case we might find the first idea morphs into something the originator of the first shape did not intend. We can infer from this that greater complexity and more information define an abstraction more precisely and more uniquely. So in the case of the Christmas tree the first student draws a triangle. The second adds two more to make a tree shape. The first adds a star on the top so the tree becomes a christmas tree and so on. A triangle start could equally be a woman’s skirt or a pyramid. Adding arms legs and head would then start to define it as an abstraction of a female, adding blocks and putting next to a picture of a Sphinx makes it a pyramid. Notice that the context of an abstraction can help reduce ambiguity about what it is intended to be.
  • Common use of abstractions is in road signs and other simple icons that represent more complex physical objects. Another game to play is taking complex objects such as a car and representing it with the simplest abstraction that a partner can recognise as a car. Doing this in a vector drawing program such as Inkscape will also help develop computer drawing skills. Vector drawing packages are a very easy to understand implementation of abstraction in software engineering since drawings are built up from simple objects that can be grouped to form other larger more complex objects. By adding detail (information) such as textures to surfaces, drawings become more and more realistic. In the software each object will have a corresponding piece of code, effectively a code abstraction of the drawing object.

 

1.2 I can use data patterns to represent physical objects.

Candidates should be able to relate images to patterns of data.

Evidence: from assessor observations, documentation in portfolios.

Additional information and guidance:

  • Candidates should be given a lot of opportunities to think of images in terms of patterns of dots. This can start with looking at printing images to paper at various resolutions, investigating pictures in magazines or newspapers using magnifying glasses and low power microscopes. Can they use a microscope to work out the resolution of an image by counting the dots? What happens if you move your eye further away from a grainy image? Use Inkscape www.inkscape.org or similar drawing program to make a 5 x 5 grid. Fill in squares to make letters. Some letters like L or E are easy to get a good representation. M and W are much more difficult. How could we make it easier? Use a grid with more squares. Note that saying use a bigger grid is ambiguous as it could mean just bigger squares which would not help. More squares gives us more information, bigger squares are just the same information magnified. This is why with telescopes and microscopes magnification is not as useful as resolving power. Resolving power lets us see the details, magnification just gives a bigger view of the same level of detail and keep magnifying and you just get a big blurred image. This can be related to the work on abstraction. More relevant information means clearer more specific results. It is a universal principle whether dealing with images, economics or the environment.​

  • A challenge. Your friend has 4 pencils. One red, one blue, one green and one black. You have only a black pencil and you can only write the numbers 0, 1, 2, and 3. You have a 20 by 30 grid on a sheet of paper and you want to send your friend enough information for them to draw the Republic of the Gambia Flag.

  • Send you friend a grid with the information they need to create the flag. They will do the same for you and see if you both get an identical flag at the end. Can you think of any ways you could reduce the amount of information you need to send?

  • As an extension to this consider getting other colours. Since all colours are made up from red, green and blue we can combine red, green and blue in different amounts to get all the other colours. If we had 3 levels of red, 3 levels of green and 3 levels of blue, how many colours could we make? Make a 3 x 3 grid for R1, R2, R3 and G1, G2, G3. 9 possibilities. add another 3 making the grid a cube and its 27. 3 x 3 x 3. So how many colours from 255 levels of red, 255 levels of green and 255 levels of blue? This is getting well beyond what is required at level 1 but provides a good grounding for Level 2. Ideas of file compression can be opened up by an instruction to print “1” 30 times rather than writing “1” 30 times to print a red stripe. A way of doing that would be to say if there is a change of colour, the first number tells you how many of the next number to print. So 30, 1 would replace 111111111111111111111111111111. We are allowed to use 3 and 0 so this would work as long as the person at the other end knew how to decode it.

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1.3 I can follow instructions to develop a software abstraction

Candidates should be able to follow a set of instructions accurately to get a working abstraction

Evidence: from assessor observations, content of learner portfolios.

Additional information and guidance:

To achieve an abstraction in software a simple case would be to draw a box in logo with REPEAT 4 [FD L RT 90] The size of the box depends on the parameter L. We could add more parameters to change the colour and texture of the box. At this level the simplest cases are sufficient. A software abstraction is using some code to make a simple model of something in the material world and usually it is is an approximation to the real thing achieved by eliminating some of the details. The simplest abstractions such as drawing a line to represent a road or a circle to represent a stick person's head or a triangle for a skirt can all be represented in simple code. If a set of instructions are provided for the candidate to follow in order to get a working program, these constitute an algorithm. We then have an algorithm to produce the code and the code itself is an algorithm to produce the abstraction. The success of the algorithm to produce the code depends on how much information the programmer needs and for sufficient detail to be provided to them that they can understand. Similarly the success of the code as an algorithm depends on its accuracy and the ability of the computer programming language to understand the code as specified by the programmer. If both algorithms are well designed, the output will be as expected.

 

1.4 I can use software abstractions that model real world systems

Candidates should be able to use software models of real world systems.

Evidence: from assessor observations, schemes of work, content of learner portfolios.

Additional information and guidance:

 Any use of a computer simulation of a real world system is a target for this criterion. Numpty Physics http://numptyphysics.garage.maemo.org/ is a free and appropriate example that should help learners of this age understand the principles of abstraction since it is a simplified representation of the physical world.

 

1.5 I can identify strengths and weaknesses in computer models

Candidates should be able to list strengths and weaknesses in models that they use.

Evidence: From content of learner portfolios.

Additional information and guidance:

If we take the Numpty Physics model, strengths are that is fun and easy to use, weaknesses are that the representation of reality of real objects is visually very approximate. Of course that is also a strength in relating to general physical behaviour in a fun way. In general, encourage debate about why things are considered strengths and weaknesses. A lot of unnecessary detail could provide little benefit and make the software a lot more expensive or demanding of the hardware and it might actually be less fun. The interesting issues are usually the ones where there can be disagreement. This is also an opportunity to review games and to develop descriptive language beyond "I like it" or its good to say why it is good and to see if there is consensus. Another aspect is to identify strengths and weaknesses in coded algorithms. For example, where code is badly documented, inefficient, or particularly elegant. These aspects are very much more difficult to assess except in superficial ways in controlled tests so encourage understanding in the course of normal activities through, for example, peer review.

 

2. Candidates will understand algorithms

2.1 I can write algorithms for everyday tasks

Candidates should be able to use ordered lists of instructions to define procedures for everyday tasks.

Evidence: Assessor observations, local testing, portfolios.

Additional information and guidance:

Algorithms are step-by-step problem-solving procedures. It is really a "fancy" word for something everyone does every day if they have any routines. Get up, go to the bathroom, get dressed, go down stairs, put the kettle on. All that is required here is that candidates can list the steps in everyday tasks. They should appreciate that repetitive tasks that are simple to replicate lend themselves to algorithms. Complex unpredictable behaviour doesn’t. For example riding a bike to school. Mount bike, repeat (pedal) until I’m at school, dismount, park bike. Of course this is very simplified since we are saying nothing about avoiding traffic or turning corners. In practice a full algorithm that took into account all the possible events that might take place on the journey is a whole lot more complicated. It would be very difficult if not impossible to write an algorithm to coincide with how an individual lives for a month.

 

2.2 I can identify different algorithms that target the same task

Candidates should be able to recognise at least two different methods of approach to a problem that lends itself to an algorithm

Evidence: Assessor observations, local testing, portfolios.

Additional information and guidance:

 

  • A bubble sort and a merge sort are both sort algorithms but they can result in different efficiencies in achieving the outcome. A linear search and a binary search are again different methods targeted on the same problem. At level 1 candidates would be able to determine that two methods are achieving the same result even though the methods might work differently.

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2.3 I can compare algorithms

Candidates should be able to compare algorithms based on properties such as how easy they are to follow or understand, how efficient they are and the circumstances where they might work and not work.

Evidence: From local testing and portfolios

Additional information and guidance: 

Candidates should be able to see that some algorithms are easy to follow and some are much more complex. They should be critical of algorithms that are not documented well enough to understand. They should be able to carry out simple tests comparing eg two sort algorithms to see which is the most efficient. Guidance should be provided on the need for controlling variables such as the number of items to be sorted or searched so that the test is fair. This would be a good aspect to relate to the science curriculum. A mixture of algorithmic games and activities away from a computer and some with code will help in developing transferable understanding.

 

2.4 I can apply logic to efficiency and effectiveness of algorithms

Candidates should be able to provide rational reasons why they would prefer to use one algorithm rather than another.

Evidence: From assessor observations and portfolios

Additional information and guidance: 

As part of their testing of algorithms, they should be able to provide reasons why one algorithm is more suited to a task than another. This might need reference to a particular context such as search strategies in a game of "Battle Ships". http://csunplugged.org/searchingalgorithms is a possible resource for this.

 

2.5 I can change variables in an algorithm and predict the effect

Candidates should use existing code and experiment with changing one variable at a time to see its effect.

Evidence: Assessor observations and portfolios.

Additional information and guidance:

This is another opportunity to reinforce control of variables. Experimenting with variables in several different scenarios should enable candidates to make predictions about effects in simple but unfamiliar code.

 

2.6 I know how instructions and data are stored.

The candidate should know that instructions are stored in programs in a particular sequence and executed one after another but very quickly so that often it appears as if several things are happening at the same time.

Evidence: Internal testing, portfolios

Additional information and guidance:

  • Conditional statements in programs determine which instructions are executed and in what order. Modern processors can execute hundreds of billions of instructions in a second. If a display is refreshed 100 times a second (typical of modern screens), more than a billion instructions can be processed in that time. To the observer of the screen it could look as if several things have happened all at the same time whereas they were actually processed one after the other. In the early days of computing performance was governed by the processor clock speed. Make the clock faster and the computing power increased but so did the heat generated. In order to operate at faster speeds the components had to get smaller so processor components became more densely packed. This makes the heating problem even worse. Removing the heat fast enough without frying the processor requires large heat sinks and fans. Apart from the waste of energy, this situation is also totally useless for mobile technologies that are dependent on batteries because the battery life will be insufficient for practical use as the processor churns out heat. (Good opportunity here to link to science, environment and conservation of energy) Most of the effort is now to make processors more efficient and to give them multiple cores – effectively several processors on one chip. Of course writing software more efficiently will also help. If I can find a way of making savings in the number of instructions executed in my program to get the same outcome it will be no different from improving the performance of the hardware.

  • Programs are normally executed from very fast memory actually on the processor itself (called a cache). So instructions and their associated data are stored in different places at different times. The program will be stored eg on a hard disk, pulled into the computer's main memory but the codes being executed will be in faster memory better matched to the speed of the processor. Why not just run all the memory faster? Cost. It is very much more expensive to manufacture faster memory so it is a trade off between capacity and speed at a particular price point. Hard discs are slow compared to RAM but 1000 GB of hard disc space is a lot less expensive than 1000 GB of RAM. With mobile technologies hard discs consume more power and are relatively bulky and the devices can store their information on the internet. At the time of writing there appears to be a transition taking place from desktop and laptop computers to mobile technologies based more on power efficiency and small energy efficient clients to internet based resources. These are all areas worth exploring as they will have an increasingly significant impact on learners in the coming years. The main requirement for learners for this criterion is to understand the basic concepts of storing instructions in a program and executing them in a program flow.

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  • In a sense, writing any program code is using codes to represent instructions and data. The HTML tag <h1> is a code telling the browser to make the following text adopt a particular style. </h1> is telling it to stop. HTML is a good way of introducing these concepts because it is practical, simple and accessible. <strong> will make the text appear bold and </strong> switch this off. Characters between the tags are data. They are simply displayed as written. So the tags represent instructions and what is between the tags is data. HTML is a mark-up language rather than a programming language because it doesn't have structures such as loops and conditional statements. These are added by using Javascript. (Note Java script is nothing to do with Java!) For the purpose of this criterion it is sufficient for learners to understand tags are codes representing instructions and anything that isn't a tag is data.

2.7 I can identify situations where codes control events and record physical data

The candidate should be familiar with machinery that is controlled by code and measuring instrumentation that is automated.

Evidence: Assessors observations, portfolios

Additional information and guidance:

Typical examples are 3D printers, robots, CAD/CAM, working models such as Lego, Fischertechnik and similar kits. Candidates should preferably have some hands on experience of programming practical control systems where the code controls physical events. It is true to say that there is an element of this in general purpose computing since software controls mechanics in printers, disc drives and other peripheral devices, however, breadth of experience will help in transfer of learning to unfamiliar and new situations. This would be a good opportunity for links to science in terms of measuring and recording data through experimental investigation and in creating products in design and technology.

 

3. The candidate will use programming languages

 

3.1 I can originate useful code in a visual language

The candidate should be able to originate some useful code in a visual language such as Scratch or Blockly.

Evidence: Portfolios

Additional information and guidance:

Candidates should be encouraged to code complete projects but given time constraints they could adapt and modify existing code as long as they can originate at least some of the code themselves. The challenges in Blockly at https://code.google.com/p/blockly/ are a good way to get started.

 

3.2 I can originate useful code in a text based language

The candidate should be able to originate some useful code in a text based language such as Logo, python, BASIC, Javascript or Java.

Evidence: From candidate's source code in portfolios.

Additional information and guidance:

Candidates should be encouraged to code complete projects but can be provided with sufficient structured guidance as long as they can originate at least some of the code themselves. Blockly is free from the web and enables export of code to Javascript and Python. This provides a good potential means of transition from visual programming in Blockly itself to programming in Javascript or Python.

 

3.3 I can identify structure in programs

The candidate should be able to identify variables, procedures, loops and conditional tests in existing programs.

Evidence: From assessor observations, internal tests.

Additional information and guidance: 

Candidates should be given opportunities to review source code that is sufficiently well documented for them to identify key structures and decide how they relate to the outcomes produced when the program is run. They should be encouraged to adopt good structural practices in their own work. They should be able to see how tables of data can be separated from program instructions and how a very large and complex program can be made up from many much simpler components. They should become aware that good structure and clarity are desirable eg by using peer review. Do other people understand their work and do they understand the work of others?

 

3.4 I can test code

The candidate should be able to use pauses in program code to identify the places where errors occur.

Evidence: From assessor observations and documentation in portfolios

Additional information and guidance:

Being systematic in approach to finding and isolating bugs is the aim. Candidates at level 1 will need clear and concise instructions to support their work. This work could be related to the work on comparing algorithms and also to control of variables.

 

3.5 I can edit source code to fix a bug

The candidate should follow instructions to make simple edits to source code to fix bugs.

Evidence: From assessor observations and documentation in portfolios

Additional information and guidance:

Level 1 candidates will need support and clear instructions in any but the very most straightforward cases. A key point is to immediately check any edit so that the effect of the edit is obvious. Avoid trying to fix several bugs at the same time since additional bugs can be introduced unintentionally and then it is not so obvious which edit was responsible. This might be a good time to introduce the concept of "many eyes making bugs shallow" and encourage working in pairs. They should also appreciate the importance of access to the source code if bugs are to get fixed, and also to really understand what a program is doing.

 

3.6 I can choose variable names that aid clarity

The candidate should spend time choosing variable names that are meaningful in the context of their code.

Evidence: From source code in portfolios

Additional information and guidance:

This is all part of documenting source code to enable maintenance and development. Other people usually take over code from the original author and so it is important for them to be able to quickly understand the software. At one time there was an argument for short labels and names because the space available to run programs was very limited. This is no longer the case and the only reason for using short and cryptic variable names is laziness.

 

4. The candidate will understand Boolean Logic

 

4.1 I can predict the outcome of statements containing AND, NOT and OR

The candidate should be able to predict the outcomes of simple conditional statements containing each operator.

Evidence: From internal testing.

Additional information and guidance:

Conditional statements are of the the form IF <condition> THEN <do something> eg IF 3 > 2 THEN PRINT "true". Involving the Boolean operator AND could result in IF 3 >2 AND 8 >6 THEN PRINT "true" AND requires both conditions to be true. If we replace AND with OR true will be the result of either condition being "true". These conditions are more powerful when the numbers are variables. eg IF A > B AND X > Y THEN PROCEDUREgreaterthan. So if A is a bigger number than B and X is a bigger number than Y do some processing contained in a PROCEDURE called greaterthan. NOT effectively inverts a condition. IF NOT A>B PRINT "B is bigger than A". Candidates should be able to predict the results of simple statements of the type presented here. This will need some practice. Some clear supporting resources are at http://computer.howstuffworks.com/boolean1.htm and http://www.cuttheknot.org/game_st.shtml

 

4.2 I can include AND, NOT and OR in information searches

Candidates should be able to use the equivalents of AND, NOT and OR in searches using a particular search engine.

Evidence: From assessor observations and internal tests.

Additional information and guidance:

Modern search engines are very good at finding relevant information without much need to know about Boolean Logic however they normally provide ways of including operators in searches. As an example, Google provides the following information https://support.google.com/websearch/answer/136861?hl=en. The whole indexing of searches and the algorithms used to work out relevance is very complex. This link provides and overview http://www.google.com/intl/en/insidesearch/howsearchworks/thestory/. At this level candidates should realise that searching a list is easier if you sort it first. The activities in Computer Science Unplugged http://www.cuttheknot.org/game_st.shtml on algorithms is relevant here.

 

4.3 I can identify reasons why some search results are likely to be more important than others

The candidate should know some factors that search engines use to decide which sites are the most important.

Evidence: Internal testing, portfolios.

Additional information and guidance:

  • Although not published in detail, Google uses over 200 factors in ranking the importance of sites for searches. These include.
  • Links – links to and from the site, the quality of those links, and ratios between links and even links with pages on the site and how it interrelates and how often it changes and the rate of change.
  • Site content – the content of the site, keyword density and interrelationships of content on the page and content within the site itself and how it interrelates and how often it changes and the rate of change.
  • Visitor related factors – how many visitors return, how many visits the site receives and the rate of change (increase or decrease) of new visits.
  • Domain name factors – How long the domain name has been registered for and how long it has been owned. How many times it has changed ownership.
  • Why does Google not publish its search algorithms in any detail?

 

4.4 I can relate boolean logic to program flow

Candidates should be able to identify the use of Boolean Logic in existing code, saying broadly how it affects the routes of program execution.

Evidence: From assessor observation and portfolios

Additional information and guidance:

The code studied should where possible have relevance to the candidate's interests, projects or other work. Conditional statements such as IF, WHILE, CASE, etc. More of this at https://en.wikipedia.org/wiki/Conditional_(computer_programming)

 

4.5 I can use search techniques to improve efficiency of finding information

Candidates should be able to replace parts of words with wild card characters when performing searches or other techniques.

Evidence: From assessor observations

Additional information and guidance:

The most appropriate place to demonstrate this is likely to be searching for files on local systems. Wild cards tend not to be very useful in general search engine type searches because the number of matches is likely to be enormous.  On the Internet candidates can use words in quotes to imporve finding the words they require, therefore typing "computer files" will return information about computer files, whereas computer files without quotes will return all pages with computer and then all with files and finally all with computer files.

 

4.6 I can represent numbers using binary patterns

Candidates should be able to represent decimal numbers by binary patterns and use codes to represent letters and characters.

Evidence: From assessor observations, local tests and portfolios,

Additional information and guidance:

There is a good introduction to binary numbers in http://csunplugged.org/activities. More resources at http://www.convertbinary.com/

http://home.paulschou.net/tools/xlate/

http://www.mathsisfun.com/binarydecimalhexadecimalconverter.html

http://nickciske.com/tools/binary.php

  • At the most fundamental level all instructions and data are stored as voltages. A 0 voltage is zero, and voltage significantly higher than zero is 1. All the sophistication and complexity of all computer systems boils down to this. The 1s and 0s are called binary digits or bits. 8 binary digits makes a byte. If we set 8 wires to each have 0 volts we have 0 and if we set each to say 5V we have 11111111 = 255. Why 255? Because there are 255 possible patterns using 1s and 0s on 8 wires. Every time we add another wire we double the number of possible combinations. So 9 wires will give 512 and 10 will give 1024 and so on. (See CS unplugged for binary activities) The original microcomputers popular in the early 80s were 8 bit. Now the norm is 64 bit. No great fundamental difference except that if each instruction is represented in 8 bits, a 64 bit processor could process 8 at the same time. That is quite apart from the clock speed increases to make them go faster.

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  • 8 bits has a special significance in computing because it is the fundamental unit for many codings. eg all the numbers, letters of the alphabet and characters such as £,*,$ etc each have a unique 8 bit code. A letter "A" is for example code 65, B code 66, the space bar code 32. We don't need to remember these because computers do the translations automatically although it is easy to find tables of them http://www.ascii.cl/ Computers are in fact translating the binary patterns to the numbers and letters we see on the screen. The decimal numbers are really just because most humans are more familiar with them. So a set of 8 wires representing the letter A or code 65 would be 01000001. where 0 is zero volts and 1 is a higher voltage. Storing the letter A in RAM or on a hard disk means there is a tiny area on the disc or in the chip with that pattern on it in some physical form. If we could make them say ionised and unionised atoms, each letter could be represented in the space of 8 atoms. Currently it takes about 10 million times as much space. The theory is a lot easier than the practical technology though!

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  • Candidates should be able to tackle simple problems such as if I have the bit pattern for the letter A 01000001 how would it change to a letter B given that A is 65 and B is 66? We need the next number up so it is 01000010. They should appreciate how counting in binary works.

  • They can make secret messages in binary and use the converters to decode them. Of course not that secret if other people have access to the decoder. They could of course write some sort of binary encoder eg changing all the 1s to 5s and 0s to 4s so that a binary decoder would not work unless they first put the message through something to convert the 5s and 4s back to 1s and 0s.

  • A lot of scope here for coding games, secret messages and similar.

 

Unit 2 – Using digital applications to support projects

1. The learner will be able to select use and combine applications

1.1 I can select suitable applications to support my work

Candidates should be able to match some common applications to the specific tasks such as a drawing program for designing graphics, a text editor for editing text, a spreadsheet for making number models.

Evidence: from assessor observations, documentation in portfolios.

Additional information and guidance:

Candidates should be encouraged not to just take every application on face value and experiment with some different tools, especially free resources from the internet and not restrict their experience to particular types of computer eg desktop, tablet, smartphone. There is really no need to spend money on licenses for most general productivity tools and this also enables students to legally use the same tools outside school as in school therefore contributing to inclusion. Two of the key changes taking place globally in technology is a shift to open standards related to the internet and the increasing takeover of mobile technologies. In relation to open source, a simple example is graphics. There are three fundamental open standards for graphic images. .jpg, .png and .svg. These cover nearly every possible requirement and should be encouraged as replacements to older and less efficient formats such as .bmp, .gif, .cdr, .ai and similar formats. Note that proprietary vector formats such as .ai tend to create monopolies by forcing use of the software that created them. .svg is the open internet (XML) based vector standard and Inkscape is a free and open source application for editing .svg files and exporting .png files from them. While .svg has taken some time to establish itself, it is in everyone's interest to promote open standards because it frees up competition in the market and therefore reduces costs and increases convenience to end users. It is generally bad practice to design graphics in applications such as Word or Publisher even though at this level it is practically possible and in some cases might appear easier. It is better to learn a specific application that is designed for the purpose and produces files in the open standard. Where possible originate graphics as vectors and then produce raster graphics such as png and jpg from the vector. This is because the vector application is the best for designing in and it produces infinitely scalable images without problems of resolution and enormous file sizes. .png files are for displaying line diagrams where the eg browser software is not yet up to coping with .svg. A .png can have transparent objects and does not lose any data due to file compression to reduce the size of its files. .jpg can not have transparencies and trades off quality for low file size. Both .png and .jpg can be used for photographs but usually .jpg is the best format for these. .svg can produce photo-realistic drawings and can contain a photograph as part of a file but photographic images can not normally be converted to vectors. Similar arguments can be made for audio and video formats but at this level graphics are likely to be the most common scenario where some basic knowledge will make a significant difference to dealing with practical and unfamiliar circumstances.

1.2 I can collect and record data

Candidates should be able to use digital devices to collect and record data in useful situations

Evidence: from assessor observations, content of learner portfolios.

Additional information and guidance:

The most commonly cited use of data recording is in experimental measurement in science. This is still a perfectly legitimate activity to support this criterion. An example might be recording the temperature of a liquid as it cools and freezes. Note that all data recording boils down to sampling a changing voltage and storing the samples as bytes of data. The device that converts the physical thing (temperature, sound intensity, brightness of light, etc) into a voltage is called a transducer. A microphone is a transducer for sound, a digital camera for light. The chip that converts a continuously changing electrical signal into digital data is called an ADC – Analogue to digital converter. A 16 bit ADC will divide up the signal into about 64,000 parts. If it was used with a transducer across 100 degrees a theoretical accuracy of 1/640th of a degree would be possible. A 8 bit ADC would divide into 255 parts so better than 0.5 degrees accuracy which would be good enough for a lot of general purpose temperature measurements. Level 1 candidates will not be expected to know about how data recording works but it could be useful background for some for Level 2. Using software such as Audacity to record audio data effectively and outputting it to appropriate file formats is typical of what is required. Being able to relate the size of the data file recorded to the length and quality of the recording will be useful too. Most technical problems arising from data capture are due to a lack of understanding of file sizes and file types. The more experience candidates can get of this, the more confident they will become in unfamiliar contexts.

1.3 I can find patterns in data

Candidates should be able to see patterns in their data and in simple cases relate them to physical effects.

Evidence: from assessor observation and content of learner portfolios.

Additional information and guidance:

In the case of audio recording candidates should see that the amplitude of the signal is related to the loudness of the sound and that shorter wavelengths are associated with higher pitch. Other patterns might include variations in brightness eg measuring light intensity over a day and night. The exact examples are up to the assessor to provide but candidates should gain enough experience to relate simple patterns to physical circumstances in unfamiliar settings.

1.4 I can present data effectively

Candidates should be able to present data in tables and graphical forms subject to guidance in keeping with level 1 qualifications.

Evidence: From content of learner portfolios.

Additional information and guidance:

Candidates should be regularly reminded of how easy it is to misrepresent data. They should be guided to present simple data informatively with the emphasis on clarity and objectivity in straightforward situations. An example might be to present simple information in a web page by combining the output from a chart drawing program or spreadsheet with text in a content management system web page. The subject could be showing the time they spend each week in different lessons, the number of people in their class who have a birthday in a particular month, the results of a scientific investigation. Try to avoid stereotyping the word presentation with particular proprietary software brands and giving the impression that one piece of software can be used to do everything. Part of the learning process is to develop flexibility in using and combining different applications and so even if it is possible to use a single software resource is is desirable to combine several simpler tools. Issues that arise in data transfer and compatibility will provide useful learning to make the candidates more able to transfer their learning to new and unfamiliar circumstances.

1.5 I can meet the needs of other people

Candidates should be able to present data in tables and graphical forms subject to the structure and guidance in keeping with level 1 qualifications.

Evidence: From assessor observations and learner portfolios

Additional information and guidance:

Candidates should use a brief to produce something that is useful to other people. They should be encouraged to combine applications to do this and the work can include programming or scripting. This is an opportunity to undertake a small scale project that can support this and other learning outcomes. Software is becoming increasingly capable of “guessing” user needs. Mobile devices are increasingly “context aware” so for example, when you are standing next to a bus stop the device senses it and can automatically display the timetable on the screen along with how long until the next bus arrives. This can be related also to criteria for data logging as it is all the same principle. While at level 1 it is not realistic to expect candidates to program context awareness into their applications they should be aware of it as a sophisticated application of what is actually quite an old technological concept. It is simply enabled by much more powerful low cost and portable devices.

1.6 I can use more than one application to solve a particular problem

Candidates should be able to combine at least two applications in achieving a solution to a particular problem or task.

Evidence: From assessor observations and learner portfolios

Additional information and guidance:

Candidates should be able to provide a solution to a problem supported by at least two and preferably more applications. An example might be to use a graphic design program and an image editing program to design and prepare clip art for display in a web page. They could use noise removal in an application eg Audacity to clean up their sound track before adding it to their video. At this level candidates will require structured guidance in keeping with the general description of Level 1 qualifications. Other examples might be producing a newsletter using a text editor and imaging software to source the content and a different application to organise and print it.

2. The candidate will be able to create original works using digital applications

2.1 I can originate original digital information from my own imagination

Candidates should be able to originate original digital resources from a zero base.

Evidence: Assessor observations, local testing, portfolios.

Additional information and guidance:

Candidates should create something original from a zero base. This could be an image designed using a vector program, rather than originating a bitmap eg from a camera, They might compose some original music or video film. The spirit of this criterion is creativity and while use of existing work is not banned where it is sensible to incorporate it, there should be a clear element of original work rather than exclusive remix of other people's work. Remix is a legitimate creative activity in its own right and it is assessed in the next criterion so the emphasis here should be on originating new material.

2.2 I can use remix to create original digital information

Candidates should be able to edit and combine existing information to create something new with an element of originality.

Evidence: From portfolios

Additional information and guidance:

There are many good examples of remix on the web. Candidates should be aware of licensing and err on the side of caution although re-mix is an area that is not as clear cut about what is and isn’t infringing a copyright license.

2.3 I can use specific design techniques

Candidates should be able to incorporate specific design techniques in their work

Evidence: From assessor observations and portfolios

Additional information and guidance

n the case of images, specific techniques include perspective, lighting and shadows. They should combine learning from the computer science unit in handling colour and file sizes. In audio applications they should be able to remove noise and edit out unnecessary pauses in, for example speech.

2.4 I can match my work to a target audience.

Candidates should make clear the type of people on whom they are targeting their original work.

Evidence: Assessor observations and portfolios.

Additional information and guidance

Two clear possible audiences are their family and younger less experienced learners. If projects are originated to support learning in younger pupils, it helps reinforce their own learning and makes the target audience clear. They can also get evaluation feedback relatively simply. The best endorsement of work is for it to be taken up to be used.

3. The candidate will be able to manage projects

3.1 I can structure a plan for a project supported by digital tools

The candidate should be able to organise a plan for a project in keeping with the general level 1 description.

Evidence: Portfolios

Additional information and guidance:

Candidates will need structured support with their planning in keeping with the general level descriptor for level 1 qualifications.

3.2 I can carry out projects by linking a sequence of steps

The candidate should be able to follow a logical sequence of steps to support the execution of their project.

Evidence: From portfolios.

Additional information and guidance:

Candidates should be encouraged to become increasingly self-sufficient in solving their own problems as they go through the steps in their project. Working in a team is recommended. The main aim is to appreciate that projects require sequential steps and this could be related back to work on algorithms.

3.3 I can evaluate a project in terms of its strengths and weaknesses

The candidate should be able to identify strengths and weaknesses in the execution and/or outcomes of the project

Evidence: From portfolios

Additional information and guidance

Candidates should be able to identify strengths and weaknesses and it is a good idea to involve peer review in the process. Candidates should accept criticism graciously and provide constructive suggestions for improvements.

3.4 I can apply e-safety principles to my projects

The candidate should be aware of e-safety issues and be prepared to take action in keeping with the general description of level 1 qualifications.

Evidence: From assessor observations and portfolio

Additional information and guidance:

Being safe online is the objective. At level 1 structured support will be necessary in some areas. Part of this criterion is the appreciation and willingness to take advice from more experienced people. E-safety is important and the best way to become safe is through guided practical experience.

3.5 I can show courage in completing a project.

The candidate should demonstrate courage in persevering and making an effort to overcome difficulties.

Evidence: From assessor observations and documentation in portfolios

Additional information and guidance:

The spirit of this criterion is to recognise the fact that although at level 1 structured support will be needed, candidates are expected to make an effort to overcome difficulties themselves. Real life projects require courage to complete and this is an opportunity for candidates to demonstrate this quality.

4. The candidate will be able to respect intellectual property

4.1 I can identify licenses that are restrictive

The candidate should be able to identify copyright licenses that restrict re-use of the work

Evidence: From assessor observations, portfolios

Additional information and guidance:

Try to establish the difference between copyright and licenses. It is the license that determines whether or not you can copy a work. Copyright free should be either public domain or licensed for free use. Whenever a candidate originates work technically they are the copyright owner and they can determine who can use the work and how. Many proprietary companies license work so that it can only be used if a fee is paid. These licenses are “restrictive” because they restrict the use of the work. Just to add more confusion, copyright rules are different in different countries. In general candidates should not use anything that causes them any doubt.

4.2 I can identify licenses that are liberal

Candidates should be able to identify licenses that are liberal. These are licenses where copying is allowed but there might also be some conditions.

Evidence: From assessor observations and portfolios

Additional information and guidance:

The most liberal license is public domain. Work in the public domain can be freely copied. A good source of public domain clip art is www.openclipart.org. Your students can contribute and become famous artists! There are many liberal licenses for software too. The BSD license and Apache Software Foundation licenses allow you to do just about anything with the software as long as you respect the trademarks. The GPL is liberal but also requires you to use the same license for works you derive from GPL licensed work. Linux is probably the best known product licensed with the GPL. Creative Commons is another widely used liberal license eg by Wikipedia. At this level it is sufficient for candidates to understand the broad license types and to be aware enough to start checking. it is safest to use sources such as the wikimedia commons and openclipart to be sure to be working legally. There is usually no need to “pirate” software because perfectly good free and legal applications are available for most major and popular tasks. Candidates need to appreciate this and be supported in finding suitable applications themselves.

4.3 I can ensure my work contains only appropriately licensed content

The candidate should use peer review and quality assurance review to identify risk in using inappropriately licensed information.

Evidence: Assessor judgements and portfolios.

Additional information and guidance:

Whenever candidates get information – text, images, video, audio – to use as part of their work they should acknowledge the source and b) question whether or not what they are doing is legal. At level 1 they will need structured support and constant reminders. The objective here is to ingrain the questioning of the rights to use copyright material so that it becomes a routine part of working. They should appreciate that it is a lot less hassle to go to known sources of work that is licensed for free use. If they can’t find what they need there, is it worth paying for it? Assessors should be vigilant in ensuring candidates do not have inappropriately licensed material in their portfolios.

4.4 I can find open source equivalents for many proprietary software applications

Candidates should be able to identify open source equivalents to the most popular proprietary productivity tools.

Evidence: From assessor observation and portfolios

Additional information and guidance:

The aim here is to engender informed choice. Mostly people use software applications that are popular because they have never tried anything else. There is no obligation to use Open Source Applications but if you have never done so how do you know whether they are useful or not? The most obvious applications are OpenOffice.org/LibreOffice in place of MS Office, Inkscape as a replacement for Fireworks, Illustrator, Corel Draw, Serif Draw etc. GIMP as a replacement for Photoshop, Audacity for sound recording programs. There are also free resources on the internet that while free of charge are not Open Source. Google Docs is a good example of this. A list of popular open source applications is at http://sourceforge.net/directory/os%3Alinux/freshness%3Arecentlyupdated/?page=1&_pjax=true

Candidates should be able to name a few popular Open Source applications and how they can be acquired.

Moderation/verification

The assessor should keep a record of assessment judgements made for each candidate and make notes of any significant issues for any candidate. They must be prepared to enter into dialog with their Account Manager and provide their assessment records to the Account Manager through the online mark book. They should be prepared to provide evidence as a basis for their judgements through reference to candidate e-portfolios and through signed witness statements associated with the criteria matching marks in the online mark-book. Before authorizing certification, the Account Manager must be satisfied that the assessors judgements are sound.

Unit 3 Computer Hardware and Networks

1. The candidate will understand computer hardware

1.1 I can identify the main hardware components in computing devices

Candidates should be able to identify CPU, micro and standard USB ports, audio and video ports, RJ45 network ports, SD Cards, Memory modules, USB memory, hard drive, keyboard, mouse, displays for commonly used computer devices.

Evidence: from assessor observations, internal testing and documentation in portfolios.

Additional information and guidance:

Candidates should be familiar with commonly used hardware components through hands on use. Raspberry PI, building a PC or taking apart disused machines will all provide experience. A good little game is to provide a hardware specification for a computer and ask the candidates to use the web to source the parts at the best possible price. The winner is the one who can get the components to build a machine at the best price. If you want to make it more difficult take shipping costs into account and say you need 50 pieces. This will make it less likely that shipping costs will swamp the costs if components are bought from different suppliers.

1.2 I can match discrete components in computing devices to purpose

Candidates should be able to match a component to a description of its purpos

Evidence: from internal testing and portfolios.

Additional information and guidance:

Candidates should know the different purposes of common components. CPUs for processing instructions, USB ports for connecting peripherals, RAM for storing programs and data that is in operation, SDRAM and hard discs for storing programs and data while not being used. A heat-sink is for taking heat away from active components to stop them being damaged by getting too hot. Heat-sinks might incorporate a fan. Power supplies to convert mains voltages to the lower levels needed in the devices, Batteries for portable power. Main board to hold and enable connections between the components.

1.3 I can classify hardware on the basis of purpose

Candidates should be able to group hardware devices that have common purposes.

Evidence: from internal tests and content of learner portfolios.

Additional information and guidance:

Candidates should be able to recognise that for example, SD Cards, USB pen drives and hard drives all have the primary purpose of holding programs and data before use. They should be able to see that internal power supplies. external power supplies and batteries all provide the energy to make the computer work. Keyboards, mice and touch screens are all input devices, Screens, printers, plotters and CNC machines are all output devices.

1.4 I can compare hardware components on the basis of their properties

Candidates should be able to use the physical and performance properties of components to make comparisons.

Evidence: From internal testing and portfolios

Additional information and guidance:

Candidates should be given many opportunities to compare components and devices carrying out testing where possible. Do all computers start up in the same time? If not why not? Are all USB ports equal when transferring data? Are differences in price justified? Does over-clocking a RaspberryPI really make much practical difference? Is it worth paying more for a hard drive for capacity that is unlikely to ever get used? These are opportunities to reinforce and develop numeracy with simple calculations to quantify differences. At Level 1 structured support will be needed in keeping with the overall level descriptor.

1.5 I can identify power consumption and performance as key limits on hardware

Candidates should appreciate the tension between computer performance and power consumption.

Evidence: From assessor observations and learner portfolios

Additional information and guidance:

One of the most fundamental technical limits on technological progress is power management. Portable devices require light weight and long battery life but they also need increasing processing power and hi-resolution displays. If the speed of a processor doubles the energy it consumes doubles. If the voltage at which a processor operates doubles its power consumption goes up 4 times. So it is important to run processors at a low voltage and the processing power in every tick of its clock is also very important. Particular strategies to reduce power consumption include.

  • Variable speed processors so that the processor only runs fast when it is needed
  • Multi-core processors to reduce the need for increasing the clock speed in order to keep processing power up
  • Using low power cores in a multi-core processor design to handle some not so demanding tasks
  • Low voltage designs
  • Efficient chip designs with fewer transistors to get the same processing power.

It is worth noting that the ARM processor in the RaspberryPI, designed by technologists in Cambridge and originally at the heart of the Acorn Archimedes computers, is one of the most power efficient in the world. Similar designs are used in the vast majority of mobile ‘phone and portable devices such as ipads. While there is probably more publicity given to the very power hungry Intel and AMD CPUs in Windows desktop computers, 4 times as many ARM processors are currently being sold and that looks to increase as people start to use mobile devices as their main computers.

Improving battery technology will also help as would improving the efficiency of software. This is another reason to learn to write efficient code. It is better for energy efficiency and therefore better for the environment.

Candidates should have the opportunity to explore power and energy considerations perhaps in conjunction with other assessment criteria and there are some excellent opportunities to link to the English, science and mathematics curriculum.

1.6 I can identify cost as an issue in performance.

Candidates should appreciate the tension between computer performance cost.

Evidence: From assessor observations and learner portfolios

Additional information and guidance:

In general high performance components are disproportionately more expensive than low cost components. Add this to branding in a technically complex field and you have a potential for users to be at the mercy of salesmen! If a particular component is a limiting factor in a performance critical application it might be justified to pay a big premium on that component but often this is not the case. Salesman will use terms such as “future proofing” to persuade people to part with their money. Take a state of the art processor costing £500 and one with say 80% of the performance costing £100. There will be no obvious difference to the user in many applications and in time other factors will probably be just as important such as the amount of memory in the machine, its power consumption or the resolution of its screen. A similar situation applies to network switches and new products. New products often command a premium price as much because they are technology fashion accessories as because of their real functionality. Often in a year or two prices are half and functionality doubled. Smart users do the sums and work out cost benefits. In most cases costing is simple arithmetic. It is understanding the real benefits if technologically illiterate that is the problem. Of course some people will be happy to pay a premium for fashionable brands but at least young people should be educated to be aware of why they are deciding to make purchases. A useful debate would be “Is their school getting good value from its technology suppliers?” How would they know?

2. The candidate will understand the role of network servers

2.1 I can identify a server in a network diagram

Candidates should be able to appreciate the server in relation to other components in the network.

Evidence:  local testing, portfolios

Additional information and guidance:

Candidates should be able to identify a server in a network diagram by considering size, shape and position in relation to other components.

2.2 I can identify a range of servers and services provided by servers to networks.

Candidates should know that a server provides a range of services including running programs and presenting results to clients, storing client data and information, enabling communication between clients.

Evidence: From local testing and portfolios

Additional information and guidance:

  • In the early days of microcomputers, servers were often called file servers because that was their main function. They stored files and shared them between clients subject to permissions to access them. They would provide shared printing services and perhaps email but they did not run general applications programs. Increasingly servers do both jobs. They run programs and the results are displayed on the client computer and they store files and handle e-mail. It is very expensive to have software applications stored and run individually on every network client, not only in the cost of multiple software licenses but in having to manage the software on every machine. Even though to an extent this management can be made more efficient using the server to update machines, in practice constantly upgrading hardware with different specifications that can not all cope with exactly the same software results in expensive complexity. Running everything from servers is potentially much more efficient and much less expensive but two things made this difficult. One is that the servers needed to be very powerful (expensive) to cope with running very large applications often designed at the limit of hardware capacity and the other is that the network connections have to be fast too.

  • The internet has changed the way we think of servers and the key is the web browser. Web browsers can run client side applications in the client eg in Javascript and also support transactions on the server side eg executing PHP code to process database information and then present it on the client through the browser. It is very much easier to manage a large server farm with consistent software than to manage many distributed client computers, scattered all over the world each running an unpredictable range of applications. The browser has effectively standardised the operating platform removing licensing fees and enabling competition based on service. At the time of writing we are in a transition to mobile clients where power consumption is just as important as performance and perhaps more so when servers can provide almost unlimited storage and raw processing power. Clients can still run their own apps but the main productivity tools can be provided and managed centrally.

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  • For this criterion, candidates need to be able to distinguish between servers processing data, storing and making information available and enabling communications.

  • The most obvious case of programs running locally is the client operating system such as Windows installed on the local machine. An example of a server running the program on behalf of the client is a search engine like Google. You make the query in the web browser and the search engine somewhere on the web then runs a program to find things linked to the query and returns the results in the local browser. An obvious data server is a file sharing application such as Dropbox. Dropbox enables the sharing of data files over the internet. The distinctions between running programs locally and running them on the server is now much less clear-cut than at any time in the past. Web pages use HTML files to tell the browser what to display but there is generally no interaction for the user. To provide that Javascript is built into the browser. Programs that run in the browser are running locally but these are usually small and could be downloaded into the browser from the server or they could be a plug-in on the local machine. The cooperation between server and client in running programs has become much more closely linked with the internet. Peer to peer systems are effectively making any machine on the network a potential server. The trend is to racks of many low cost machines, often just the main boards and components, sharing the tasks and so what is represented as a server by a box on a diagram might in fact be very many servers not just one machine.​

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2.3 I can identify key services provided by internet servers

Candidates should be familiar with internet services provided by servers, including web servers for sending out web pages, proxy servers for caching information locally, database servers and video servers.

Evidence: From assessor observations and portfolios

Additional information and guidance:

Server based services is a complex area and at this level it is sufficient for candidates to know that web servers are responsible for hosting web sites. One server can host many web sites sending out pages when requested. On the other hand a very busy site such as the Google search facility can be spread over many servers. Local proxy servers can store often used information locally so that it can be retrieved quickly rather than being limited to the slower and contended bandwidth of the wider internet. Most of the web is supported by databases. A web site of any complexity is a data base on a server with web pages through which information is presented in a web browser. Since the software protocols and associated technologies to link the data to the web page are free and open for all to use, the systems encourage competition between technology companies resulting in all web browser software being free of charge. There are commercially licensed applications built on these free and open technologies and the language for database software development (SQL) is common to both free and proprietary software. This generates a rich, varied and competitive market that has accelerated innovation and reduced costs.

Video is a sort of holy grail in that it is so data intensive that if a server can handle video streaming it can probably handle anything else. Google owns around 1 million servers at the time of writing. Probably a very significant proportion is used by You Tube. This is why it is better to make links to a site like You Tube than to host your own videos if these are likely to be used intensively. Google’s servers run on Linux, imagine how much they save in license fees by using open source software on 1 million machines. Note that servers on the internet do not have to run any particular operating system as long as the information comes to them and leaves them in standard formats. This is the reason for HTTP (Hypertext transfer protocol) ftp (File transfer protocol) and smtp (Simple Mail Transfer Protocol.) They are standard ways of transferring information independent of particular server technologies.

2.4 I can identify key factors that can affect server and network performance

Candidates should be familiar with the following key factors. For servers, processor speed, RAM, and speed of getting data into and out of the machine. For networks the rate of data transfer and the way data is routed through the network.

Evidence: Assessor observations and portfolios.

Additional information and guidance:

  • Three fundamental factors governing server performance are the speed of the processor, the amount of RAM in the machine and the capacity to get data into and out of the machine. It won’t matter how fast the processor is if the machine runs out of memory and starts trying to access information from its hard drive. This is because the speed of getting information from a hard disc is much slower than from RAM.Approximately 200ns (nanoseconds) to access RAM compared to 12,000,000 ns to access the hard drive. This is equivalent to what's normally a 3.5 minute task taking 4.5 months to complete! RAM is expensive and a lot of the time it is not used. This is why sharing RAM across a million servers is much more economic than having a million individual machines any of which might run out of RAM while several neighbours are empty. Load balancing across multiple servers minimises the chances of using their RAM inefficiently. A simple game to illustrate the point. Get 10 children to partner 10 others. One partner leaves the room the other holds as many sweets in one hand as they can. Now get them to put the sweets in a box. The sweets represent the full capacity of the children together. Now bring in the partners and say they have to get as many sweets from the box into the hand of their partner as possible, if they drop any the sweets are lost. It is likely that they will try to grab more sweets than their partner can hold so some sweets will get lost while others will have spare capacity. We know that if they are careful and work cooperatively they can all get the maximum amount of sweets but if they all come in a rush to one box and try to distribute to their partner they won’t be able to cope with them even though some of their colleagues will have spare capacity. At the end say they can share equally the sweets that all have safe. If they knew that at the beginning would they have done things differently? This demonstrates the value of load balancing (and also human cooperation).

  • If the data coming into and out of the server is such that the connection of the server to the network is saturated this will also over-ride the speed of the processor or the amount of RAM in the machine. Let’s say the machine has 4GB of RAM free and data is coming in at 100 MB per second. How long before the RAM is full and data has to be swapped to the hard drive? about 40 seconds. At this point the speed of transfer to the hard drive is likely to be the limit because this will be hundreds of times slower than taking the information into RAM. Of course if the entire Database is capable of fitting into RAM and that is all you are dealing with the hard drive might never need to be accessed and so the processor and the network connection would be the only things to consider. If the application required a lot of complex calculations the processor could be the limit. If not the connection speed could be the limit. Candidates should appreciate that it is impossible to say exactly what will be a limit unless you know exactly what the server is going to be doing. Simple games can be devised to illustrate these points. Get one candidate to bring books 10m across the class for three others to pick up and put on a shelf next to them. To speed up the process will it help to add a person to the three or to the one? The three children represent the processor working well within capacity. Adding another will make no difference if the supply of books is not increased. Now if the shelf is full and the shelf stackers have to transfer books to the library at the other side of the school before any more can be accepted, this is the equivalent of memory being full and having to transfer data to the hard drive. If they can take 3 books at a time to the library it will be faster than taking one but still won’t make much difference until the shelf can be refilled.

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  • These principles also apply to routing data through network switches. If switches know where to send data specifically it is much more efficient than if they just broad cast it everywhere so the relevant data does reach its target device but also slows every other device down by having to check irrelevant data.

2.5 I know about permissions and basic server security

Candidates should know that servers usually provide a variety of permissions for users to enable them to have ownership of their information and to selectively share it. They should know the importance of secure passwords and the need to respect other people’s information and privacy.

Evidence: Assessor observations and portfolios.

Additional information and guidance:

At this level it is sufficient for candidates to know that there are roles for most server applications with each role having permission to access different subsets of the information on the server. The concept of a super user who can access everything should be understood as well as the responsibilities that go with that role. Two clear types of permission are read and write access. They should know that it is possible to provide read but not write access and why this might be useful. They should also realise that different applications can have different sets of permissions for the same user. The need for strong passwords and keeping them secure should be emphasised.

3. The candidate will be able to identify factors affecting network performance

3.1 I can compare the performance of cable and wireless connections

The candidate should be able to make comparisons between wireless and cable network connections and their appropriateness in different circumstances.

Evidence: Portfolios

Additional information and guidance

Candidates should be aware of the term bandwidth meaning the capacity to transfer information and that it is generally highest in fibre optic cables, then copper cables then wireless. The main advantage of fibre optic cables is that they can carry signals a long distance with very high bandwidths but they are expensive. Copper cables are inexpensive but become unreliable at high bandwidths at lengths over 100m. Wireless has the lowest bandwidth but is very versatile in that it spreads everywhere and is essential for mobile technologies. It should be easy to demonstrate that for a few clients wireless is a good solution but if many access the network all at the same time they only share the bandwidth and performance will fall. Mobile phones work because not everyone is using their phone at the same time. When there is an emergency and everyone tries to access the network is can fail to provide connections. Note that a mobile phone is a small computer and a mobile phone network is a computer network. A good practical exercise is for candidates to make up a fly lead using a piece of UTP cable, RJ45 plug and a crimp tool. They can see how easy it is to make up a cable network. Plugging the cable into a RJ45 socket on the network and their computer connects them to the network. A home network is easy to wire up. A switch plugged into a server and then the clients plugged into the switch. Wireless is easier but wireless performance reduces with distance from the wireless access point and also if there are walls and things in the way. In a house it is not likely to be a limiting factor.

3.2 I can relate bandwidth to data transfer capacity

The candidate should be able to use the term bandwidth in situations where data transfer is important..

Evidence: From portfolios.

Additional information and guidance:

Bandwidth is commonly used as a generic term for data transfer in bits/second. This is because data bits/second represents a frequency similar to oscillations in analogue systems where frequency is measured in Hz. A direct example is in processor speed. A processor bandwidth of 2 GHz is 2 billion clock cycles in one second. If the processor has several cores it might well be possible to do several operations in one clock cycle and these could involve scores of bits. In a network with a bandwidth of 54 Mbits/second, (eg wifi 802.11g) the maximum possible data transfer rate is 54 Mbits/sec. In practice it is likely to be less than this. Since there are 8 bits in a byte, the maximum number of bytes that could be transferred would be 54/8 = 6.75 Mbytes. However, data transmission requires routing and other information to go with the data so the actual throughput will always be less than this. The details are much too complex for this level but candidates should know that the standard wireless bandwidth of 54 Mbits/second is likely to transfer data more slowly than a 100 Mbits/second cable. In general terms they should be able to associate bandwidth with network data transfer speed and processor speed in simple cases.

3.3 I can explain the term "contention"

The candidate should be able to explain contention as competition between many systems sharing the data transfer capacity of a system.

Evidence: From portfolios

Additional information and guidance:

It is very common for internet services to be advertised based on the maximum bandwidth available when in fact the actual amount depends on how many other people are using the system. Where several people are using the same link to a service provider they are “contenders” for the available bandwidth. If for example the contention ratio is 50:1 it means there could be 50 people having to share that connection. If they all decide to download a video file at the same time the performance is likely to collapse! But on average over a 24 hour period this is unlikely and if one user happens to be the only one on the system at the time it will be very quick. It is possible to rent uncontended lines but they tend to be much more expensive. In a school where there is a wireless access point serving a class of laptops, the same problem arises. One way to solve this is to have several access points but then all the laptops might connect to just one of them so a system to balance out the connections is needed. This again adds cost. If we take the main server in a school and its connection to the internet we have effectively the whole network through one link that is a lot slower than the connections between the clients and the server. This is where a proxy server can be useful. If information that is regularly used is downloaded once on the proxy server all users can use it locally from the proxy server instead of having to keep getting it from that single internet connection that could also be contended with other schools and local businesses. Of course contention also takes place for the server. More people requiring high intensity services from the server can eventually reduce the performance. At level 1 the main thing is for candidates to know the word contention and its meaning so they recognise what it means when used in for example ISP sales and advertising literature.

3.4 I can identify potential bottlenecks in network designs

The candidate should be able to identify bottlenecks in networks in simple cases.

Evidence: From local testing, portfolios

Additional information and guidance:

Obvious bottlenecks occur where many people are in contention for a limited amount of bandwidth in any part of a network. If the network speed between the client and a network switch is 100 Mbits/sec and the switch is connected to the server at 100 Mbits/sec there is no bottleneck if there is only one user. If there are 100 users each consuming 10 Mbits, their connection to the switch can handle this easily but the connection from the switch to the server will be saturated. This is why the fastest network speeds are needed closest to the server. Typically a level one candidate should be able to identify on a diagram where a bottleneck is likely to occur given the appropriate data on the components.

3.5 I can can distinguish between local and wide area networks

The candidate should be able to associate a local area network with a specific location such as a school or office building and a wide area network with links joining buildings at significant distances apart.

Evidence: From portfolios

Additional information and guidance:

  • Usually local area networks have a server connected to clients through structured cabling built on fast switches with distances between nodes no more than 100m. They don’t have to be confined to a single building but usually external building links are fibre optic cable a) because they can have greater distances without needing a switch or repeater to boost the signal and b) because metal cables are more vulnerable to lightning strikes. It gets difficult and expensive making these external links if they have to go over public roads or other people’s property. Once buildings are spread out by more than a few hundred metres, it is usual to use existing infrastructure for carrying the signals eg an internet service provider. Networks that span large distances are called Wide Area Networks (WANs) those using entirely their own cables, switches and access points are Local Area Networks (LANs). LANs can carry data faster and the owner has freedom to customise it any way they want but this is also expensive in management and maintenance. WANs can be centrally managed and benefits from economies of scale in principle reaching anywhere on Earth. The problem with WANs is simply the relatively slow connection between buildings separated by large distances. It is possible to get a fast connection but it tends to be expensive. The internet has driven wide area connection technology to become faster and less expensive. Another significant factor is designing software to work efficiently over a network using many smaller applications working together rather than one massive one. The internet is effectively a global wide area network with parts localised for specific uses.

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  • Your home hub is connecting your computer directly to the service providers server(s). You don’t need a server at home. Computers like the Google Chromebook are intended to work through a web browser. All of these changes are gradually chipping away at the original concept of a local PC connected for communications to being an network device that happens to be able to do some things locally. The traditional view of LANs and WANs might well change as more local needs can be satisfied by “cloud computing” where a client is connected to a website somewhere out on the internet. Of course that web site is hosted on a server or servers somewhere. There is commercial pressure as it is a lot less expensive to run eg a school’s IT infrastructure from the “cloud” but there is also pressure from the rise in mobile computing where people expect to get their information anywhere any time. It will take time to change because many of the people with decision making power find changing the way they work and the associated technologies difficult but it is clear that the question is more how long will all this take rather than if it will. For younger learners we need to consider the world in 10 years time not now and one thing is for sure, things are going to keep changing so learning how to cope with change is important.

3.6 I can identify protocols used in networks

The candidate should know what a protocol is and be able to give some specific examples such as HTTP, FTP, TCP/IP and SMTP.

Evidence: From portfolios

Additional information and guidance:

  • A protocol is a way or method of doing something. In life outside technology, protocols are used so people can work collaboratively without offending each other! For example, it is part of the protocol for meeting the Queen not to turn your back on her. When giving a business card to a Japanese business person you should hold it in two hands to pass it to them and when you receive their business card you should read it carefully and put it safely in your wallet. In technology protocols enable different systems to communicate each other. Imagine you are a program and you need to send a message to another program. The other program needs to know there is a message, who it is from, where it starts, where it ends and so on. We do this ourselves with language all the time. One of the protocols of spoken communication is to use a language the two people talking to each other both understand. If you were talking to your boss at work you will automatically adjust the way you talk to be different to how you talk to your friends in a social setting. All of this is using protocols you have generally picked up growing up. Of course it is learnt because an immature toddler often gets the protocol wrong. This is often amusing and we make allowances for it. In fact these learnt human protocols are a lot more complicated than machine protocols but machine protocols have to be precise.

  • There are far too many protocols to learn about all of them so let us look at two that are at the heart of the internet. HTTP and TCP/IP. HTTP is Hypertext Transfer Protocol. You make an HTTP request when you put a web address into your web browser – http://www.gmail.com. This involves connecting to a port on the server using TCP (Transmission control protocol). An http server will be listening on that port for requests. This is where protocols come in. The http server has to know what it is listening for and distinguish it from any old random noise coming along. Once the connection is made information is sent in defined methods and received by a server that understands those methods. We won’t get into all the details. The main thing is for candidates to understand why protocols are needed and in general terms, what they are. FTP, file transfer protocol is used for sending and receiving files and SMTP – simple mail transfer protocol is used for sending mail messages. In a nutshell all these protocols are about sending and receiving information so that sender and receiver both understand the message.

 

  • At level 1 it is sufficient to know a protocol is a way of providing information in a standardised format so that all devices that understand the format can send and receive the information reliably. They should recognise the names of some common protocols but do not need to know how they work.

4. The candidate will contribute to good network security

4.1 I can work to support an acceptable use policy

The candidate should show that they can work consistently to an acceptable use policy over a prolonged period.

Evidence: From assessor observations.

Additional information and guidance:

The INGOT community learning site has a simple acceptable use policy and schools usually have one of their own. Either of these is suitable. If a candidate abuses the system they should be expected to show several months “good behaviour” before this criterion can be safely awarded. Assessors should relate this to e-safety and citizenship.

4.2 I can choose a strong network password and keep it secure

Candidates should know the characteristics of a strong password and apply these to their own passwords.

Evidence: From assessor observations

Additional information and guidance:

Password strength depends on the number of characters and the variety of types of character. 8 characters or more and including upper and lower case letters, numbers and characters like $ and %. Passwords can be strong and memorable. eg MyDogSpot£75 or LeavesAre80%Green. Writing a password on a piece of paper is not a problem if you don’t leave the paper lying around since no computer can access that piece of paper. Candidates should not share their passwords with anyone else. This should also be part of the acceptable use policy.

4.3 I can identify encryption as a way of making information secure

The candidate should know what encryption is and some simple methods.

Evidence: Internal testing, portfolios.

Additional information and guidance:

The simplest methods of encryption are to substitute the characters in a message for a different but related set of characters. eg This is a message replaced by Uijt jt b nfttbhf. This is just moving the letters on one place in the alphabet. This is not difficult to crack! In practical encryption such as GPG the computer uses random numbers to generate a key code which the user keeps secret. The message is encrypted to very complex patterns that can only be undone if you have the key code. You only give the key code to the people you want to be able to read your message. GPG is free so it is possible to try this out. This is a resource aimed at children and another. There are a lot! Just use a search!

4.4 I can identify ways of minimising spam and eliminating malware

Candidates should be able to identify basic ways of reducing spam and avoiding viruses and other malware.

Evidence: From assessor observation and portfolios

Additional information and guidance:

Spam is unsolicited e-mail. If your e-mail address is unknown it can’t be “spammed”. A fundamental principle is not to leave your e-mail address in a machine readable format on a web site. Making an image of an e-mail address is a much better way of presenting it if it needs to go on a web site because it is much more difficult for a robot to realise that an image is actually an address. Internet searches will find many tips on reducing spam. An exercise might be to get children to work in pairs and use searches to find and then list say 5 actions to reduce spam in the order they think most important and present back to the rest of the class.

4.5 I can identify a firewall and explain its purpose

Candidates should be able to identify a firewall on a network diagram and say why it is important.

Evidence: Local testing and portfolios

Additional information and guidance:

A firewall is a software or hardware network security system that controls the incoming and outgoing network traffic by analysing the data packets and determining whether they should be allowed through or not. This is in some ways related to protocols in that the order and nature of the data in the packet will determine what happens.

Moderation/verification

The assessor should keep a record of assessment judgements made for each candidate and make notes of any significant issues for any candidate. They must be prepared to enter into dialog with their Account Manager and provide their assessment records to the Account Manager through the online mark book. They should be prepared to provide evidence as a basis for their judgements through reference to candidate e-portfolios and through signed witness statements associated with the criteria matching marks in the online mark-book. Before authorizing certification, the Account Manager must be satisfied that the assessors judgements are sound.

 

General resources

Problem solving activities

 

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