Students should then complete Task 1 2015 Controlled Assessment. Extension: Ask students to validate the data and write the data to a file (this is NOT a requirements in the original task). Homework: Ask students to complete the extension to Task 1. Task 1 (legacy specification 2013) SAM NEA Week 2 Lesson Spec ref Lesson summary Lesson content Lesson resources 1 3.3.1 3.3.2 3.3.3 Compression Starter: card sort activity in Activity 2.1.1 to elicit prior knowledge/recall of data size units. Share what students will be learning i.e. how and why computers compress and encrypt data. Remind students that bitmaps, audio and video files can be very large. Explain that compressing data reduces its file size. Ask students to suggest reasons why reducing file size is desirable (to save on storage space and speed up file transfer). Give students an opportunity in Activity 2.1.2 to discover how compression affects Week 2 Lesson 1 activities Files in Autumn term Year 11
file size. Use the ‘Honey I shrunk the data!’ animation and game to introduce three different strategies for shrinking data – ‘keep them all and make them small’ (lossless), ‘squeeze them more and open the door’ (lossy) and ‘save the best and scrap the rest’ (superchannel): . Discuss with the class the pros and cons of each strategy. Make sure that students understand the key difference between lossless and lossy compression techniques, i.e. that the former retains all the original data while the latter permanently discards some of it. Show the YouTube video ‘Run Length Encoding Visualization’ to introduce the concept of Run Length Encoding (RLE): Give students the opportunity to experience RLE compression in action by decompressing a 4-bit colour image encoded using RLE (Activity 2.1.3). Read the binary numbers aloud to students or give them the binary codes to read for themselves (see endnote ). Homework: Ask students to complete Activity 2.1.4. Resources ‘Honey I shrunk the data!’ animation and game ‘Run Length Encoding Visualisation’ YouTube video 2 Stage 1: Analysis NEA Preparation: Requirements Introduce the NEA Prep lessons (use lesson summaries). Go thought the differences between the preparation session and the ‘real thing’. Discuss the restrictions there will be when completing the real NEA (page 15 Security, and page 35 in the specification). SAM NEA Specification NEA Delivery Guide (use for
Week 3 Lesson Spec ref Lesson summary Lesson content Lesson resources 1 3.3.2 3.3.3 3.3.4 Compression: lossless run-length encoding Start the lesson by recapping why files are compressed, i.e. to make them more space-efficient and to enable them to be transferred quickly. If you feel students need more practice encoding or decompressing 4-bit colour images using RLE, you could select one student to read out their data (Lesson 1 homework activity) and ask the rest of the class to decode and draw the image. Alternatively, you could put students into pairs and have them decode each other’s images. Some groups may need to recap the data size units i.e. bits, bytes, MB. Use the 4-bit colour image in homework Activity 2.1.4 to walk students through how to calculate the size (in bytes) of the uncompressed and the compressed files, pointing out the small size reduction. Size of compressed file in bytes = number of codes x number of bits in each code / 8 = 84 x 6 / 8 = 63 bytes Size of uncompressed file in bytes = number of squares in grid x 2 / 8 = 256 x 2 / 8 = 64 bytes Explain to students the need to multiply the number of squares in the grid by 2 as each square in the grid is one of four colours, which is represented by a 2-bit number. Now give students the opportunity to do these calculations for themselves on the Week 3 Lesson 1 activities Autumn term Year 11 Programming Solutions
Activity 6.1.2 they should note this. Homework: (Activity 6.1.3). Students should produce a presentation using an application of their choice (e.g. Powerpoint, Photostory, Prezi, Powtoon) explaining the three types of data storage (magnetic, optical and solid state). Note: this homework will extend over three lessons. Images of labelled hard disk drive and surface of a hard disk drive 2 Stage 3: NEA Preparation: continue programming the solution Collect in the students Initial Test Plan. This stage is split into 3.1 Implementing the design and 3.2 Building the Solution to accommodate the marking criteria. It is expected that teachers will mark both together and that students will simply program their solution. Reinforce what can be done now but can’t in the live NEA (pages 15 and 16). Students will have four lessons plus homework time to complete their solution. Ask students to create a plan of how they are going to achieve this, perhaps by splitting the implementation of the algorithm over the allocated weeks. However it is important that they realise that this is a preparation and that they may not complete SAM Specification Pseudo-code booklet Program Syntax Guide Data file
Week 9 Lesson Spec ref Lesson summary Lesson content Lesson resources 1 4.2.4 4.2.5 Presentation of extended homework Recap the success criteria for the extended homework project. Students to prepare and use a mark sheet to assess each-others’ presentations. Presentations can be presented to the class or browsed online. Each presentation to receive ‘two stars and a wish’ or similar based on the pre-agreed criteria. Homework (Activity 9.1.1). Ask students to evaluate how they have met the assessment criteria for the extended homework. Week 9 Lesson 1 activities 2 Stage 3: NEA Preparation: continue programming the solution. Debugging tools and techniques Continue programming the solution during the lesson, and as homework. Specification Pseudo-code booklet Program Syntax Guide Data file Week 10
Week 11 Lesson Spec ref Lesson summary Lesson content Lesson resources 1 5.3.1 The internet Physical routing and DNS Starter: Either: show the network at and ask students to work out the fastest route for a packet going from Bristol to London (then as extension, the maximum delay between packets sent one unit apart). Recap the notion of IP addressing, packet switching and routers. Or: examine a selection of the screen shots of visual trace route hops students have brought in. Discuss with the class what this tells us about the way data travels across the internet. Packets can take different paths to their destination, not always the most direct; if one route is unavailable, data can be routed a different way. Explain what we mean by ‘connecting backbone’ of the internet, i.e. the high speed data routes that connect the routers and the large networks they support. Show the image from the start of the previous lesson again. Show Andrew Blum’s TED lecture ‘What is the internet really?’: Questions on the video (Activity 11.1.1). Ask students what the IP address is for the BBC’s website to demonstrate that we work better with names than numbers. Explain that this is the role of the DNS: to match up a user-friendly domain name like ‘edexcel.com’ to an . Week 11 Lesson 1 activities Visualisation image of the internet Andrew Blum’s TED lecture ‘What is the internet really?’