Teach Computing

Revision notes, activities, lesson plans, teaching ideas, and other resources for GCSE, A-Level, and IB Computer Science teachers and students.

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UK Computing Laws

This video from Computer Science Tutor covers the main UK computing laws re...

Wireless Networking (Wi-Fi, Security, and Hardware)

This video about wireless networking includes everything that is needed for...

Network topology videos

These four excellent videos from Computer Science tutor cover the four ma...

Network protocols

These four videos explain the main networking protocols that students are l...

Embedded Systems video

This short video is a good over of embedded systems, covering the main poin...

Representing Text in Binary

This video clearly explains the two main ways of representing text in binar...

Types of Malware

This video explains the various types of malware including viruses and troj...

Protecting against Malware

Following on from the Types of Malware video, this video explains technique...

Video: Network Security #1

This video gives an overview of the threats to networked computer systems, ...

Resources discount offer

C3 Distributed Approaches to the Web

These are teaching and learning resources for the IB Computer Science course C: Web science, which is an optional unit.
Click here for recommended IB Computer Science textbooks.

C.3.6 Lossy and Lossless compression

Image, audio, and text compression

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.

Updated: 2015-04-16
Text and image 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.

Updated: 2015-05-27
Run Length Encoding

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.

Updated: 2017-10-24
JPEG Comparison

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.

Updated: 2017-10-24

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.

Updated: 2018-02-17

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.

Updated: 2018-02-17