RSA encryption lesson for Pearson Edexcel International A Level Computer Science, with editable PowerPoint slides, a student worksheet and full answers. RSA is an asymmetric method that uses a public key and a private key built from two large primes; students work through small examples.

Written for Unit 3 Advanced Principles of Computer Science, topic 12 Networks and cybersecurity (specification 12.3.2). Everything is editable, so you can adapt it to your class.

What’s included

• PowerPoint lesson (14 slides) with teacher notes on every slide
• Student worksheet (Word), ready to print or edit
• Answer sheet (Word) with mark-scheme style answers for every question

U3.17 RSA encryption

By the end of the lesson students can:

• Explain why RSA depends on large prime numbers
• Generate a small RSA key pair and use it to encrypt and decrypt a number
• Describe how RSA is used for key exchange and describe its vulnerabilities

Worksheet sections: A. Key words; B. Generate a key pair; C. Encrypt and diagram; D. Exam-style questions; E. Challenge

Every lesson includes

• Learning goals and a starter question
• Clear explanations, diagrams and worked examples (Python 3 throughout, as the specification requires)
• A quick check and a “your turn” task linked to the worksheet
• Exam-style questions with marks, and an exit ticket

Format

• PowerPoint (.pptx) and Word (.docx), fully editable
• Works in PowerPoint and Google Slides
• Calm, muted sixth-form design, consistent across the whole course

These are independent resources written for the Pearson Edexcel International Advanced Level Computer Science specification (Issue 1, first teaching 2026; IAS XCP01, IAL YCP01). They are not produced or endorsed by Pearson.

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Last updated: November 2026.