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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Boolean logic worksheet pack

These three Boolean logic worksheets have exam style questions on logic sta...

Edexcel Computer Science (9-1)

by Ann Weidmann et al Amazon.com | Amazon.co.uk | Book Depository This bo...

Dijkstra's algorithm video

This video is probably the best explanation of Dijkstra's algorithm for IB ...

Input-Process-Output (IPO) Model

The Input-Process-Output model is a simple topic but some students sometime...


A comprehensive review of hexadecimal. The video covers not only how to u...

Subprograms, Local Variables & Structured Programming

Subprograms are known by several different names - methods, functions, proc...

Utility Software and Models

Some students find the difference between operating system software and ut...

Data Structures

This video explains different types of data structures - 1 dimensional ar...

Operating System (OS) - GCSE Computer Science

A detailed overview of operating systems, starting with the general tasks t...

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