Revision notes, activities, lesson plans, teaching ideas, and other resources for GCSE, A-Level, and IB Computer Science teachers and students.
Programming languages - from Scratch to machine code
The CS Field Guide has a very comprehensive guide to different types of pro...
Assembly language simulators
There are several assembly language simulators available for use online. Si...
Little Man Computer (LMC)
The Little Man Computer (LMC) is a software simulator of a simple computer ...
Lesson - Data representation - sound
This download contains all lesson resources necessary to teach students how...
Predictive placement is a feature of some CAD systems that enables more e...
AI to help emergency dispatch phone operators
The Singapore Civil Defence Force (SCDF) may trial an AI system to help tra...
Mobile Data Terminals (MDT)
MDT technology is referenced in the case study booklet, with such systems b...
TriTech Software Systems is a company that specialises in Computer Aided Di...
Spillman are another company with a range of CAD systems. Their Spillman Fl...
3.3 Data storage and Compression
Click here for recommended Edexcel GCSE Computer Science textbooks.
3.3.2 Understand the need for data compression
A short Computerphile video which explains basic compression techniques and how they can be applied to text files and image files. The video also addresses the differences between lossy and lossless compression.
JPEG Compression comparison
A simple interactive that compares a highly compressed JPEG image with a less compressed image. A slide lets you view different parts of the image. JPEG banding is particularly visible in the sky but less so in other areas - the reasons for this make for interesting classroom discussions.
3.3.3 Understand how a lossless compression algorithm works
Image Representation - Flash activity
This Flash activity lets students draw a simple bitmap image and represents it using a simple run-length encoding (RLE) algorithm in real time. Students can also important text representations of the compressed data and the application will draw the corresponding image. The web page is not in English but the application is still perfectly usable.
Image, audio, and text compression
This very comprehensive page from the Computer Science Field Guide has extensive but clear notes on lossless and lossy compression. The page is well written and designed for a high school audience, with easy to understand examples, video, and even interactive sections. There are also extension "Extra for Experts" sections. The page covers image compression, audio compression, and text compression.
Run Length Compression (RLE) interactive
This activity shows how a computer would represent a simple image when using Run Length Compression (RLE). Students can alter the image to see how the compression data would change. This is a good resource for helping students understand how lossless compression does not always result in significant size reduction.
Compression: Crash Course Computer Science
This video explains compression techniques in the context of images. It is recommended that students have an understanding of how image data is stored (e.g. bit depths) before watching this video. The video is very comprehensive and so it may take a couple of viewings to fully understand the details of the examples being presented, but it is worth it.
Lossy and Lossless (RLE) Compression
These videos from Computer Science Tutor make great revision sources. This particular videos covers the theory behind the two types of compression - lossless and lossy.