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

3.5 Security

This section covers the topics from section 3.5, to prepare students for the paper 3 (Advanced Theory) examination. Some basic computer security topics are also covered in section 1.6 Security, Privacy, and Integrity.
Click here for recommended Cambridge A-Level Computer Science textbooks.

3.5.1 and 3.5.3 Encryption Methods and Protocols

Encryption techniques

Encryption (National Codes Centre)

The National Codes Centre at Bletchley Park (who know a thing or two about ciphers) have comprehensive lesson plans, teacher's notes, and student activities for various types of encryption, from simple substitution ciphers (Caesar ciphers) through the infamous Enigma and Lorenz ciphers to modern day methods.

Updated: 2015-04-16


Very detailed but clear explanations of the various types of encryption systems, from simple substitution ciphers (Caesar ciphers) to modern public key encryption systems. The page also explains the types of attacks that can be performed against ciphers, such as known plaintext attacks and frequency analysis attacks. A variety of interactive applets held improve understanding.

Updated: 2015-04-19
Public key encryption

Public Key Encryption lesson plan

This is a kinesthetic lesson designed to help students understand how public key encryption systems work, as well as the types of security challenges such systems address. The plan includes a list of required materials and a video of the lesson being taught (this is a great help in understanding how things are supposed to work). The lesson plan is quite complicated and so is probably better suited to older students, but the analogy (padlocks) is a great way of explaining what can be a fairly confusing concept.

Updated: 2015-04-19
Public key encryption and digital signing

Public key encryption and digital signing

A short video from Computerphile which explains the weaknesses of symmetric key encryption systems and how asymmetric key (public key) encryption solves them. The video explains how public and private keys can be used for secure communication, and how the private key can be used to authenticate the sender (digital signing).

Updated: 2015-04-19

3.5.2 Digital Signatures and Digital Certificates

3.5.4 Malware

Phishing quiz

Phishing Quiz Game

SonicWALL Phishing IQ Test is a quiz game which is a great way to test students' understanding of phishing scams. Players are presented with a series of mock emails, web pages, or URLs that utilize some of the techniques online criminals often use. Spotting the the genuine pages and avoiding the fakes is harder than you might think!

Two more excellent resources are Microsoft's How to Recognize Phishing Messages and the Anti-Phishing Working Group, which both have a lot of up to date advice on avoiding phishing scams.

Updated: 2015-04-10