This module is about writing and reading algorithms in the notation Cambridge uses for IGCSE Computer Science. You will learn the conventions, trace assignment and comparison without mixing them up, describe input validation, repair a loop that never ends, and check which notation your exam year expects.
Pseudocode is not a programming language. It is a shared way of writing a method so that a person can follow it, trace it and find errors. Examiners read it as an algorithm, so the logic matters more than any exact spelling of a keyword.
What should I know before starting?
You should already be comfortable with variables, the idea of input and output, and the three building blocks: sequence, selection and iteration. If those feel shaky, work through algorithm design and repetition and arrays first.
An orienting example
Here is a short algorithm. Read it, then trace it.
Total ← 0
FOR Count ← 1 TO 4
Total ← Total + Count
NEXT Count
OUTPUT Total| Count | Total after the line runs |
|---|---|
| (start) | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 10 |
The output is 10. Notice three conventions at once: ← means “store the value on the right in the variable on the left”, keywords are in capitals, and the loop body is indented. A trace table makes each step visible, so you do not rely on a guess.
In what order should I study the lessons?
- Use the verified 2026-2028 convention: the notation itself, so every later lesson reads clearly.
- Trace assignment and comparison distinctly: the single most common source of wrong trace answers.
- Describe input validation without language-specific shortcuts: a favourite exam context for loops and conditions.
- Repair a pseudocode loop termination condition: find and fix loops that never stop or stop too early.
- Check the exam year before choosing notation: confirm what your own paper expects.
After the lessons, the mixed practice set pulls everything together with fully worked answers.
What are the common traps?
- Reading
Total ← Total + 1as a false equation instead of an update. - Using
=for assignment, or←for a test. - Writing validation with AND where OR is needed.
- A loop condition that can never become false.
- Using Python or another language’s shortcuts when the question asks for pseudocode.
How should I use the practice set and tools?
Trace first, with a pencil, and only then check. The restricted pseudocode trace trainer lets you step a short algorithm and see each variable change, and the Python reasoning sandbox shows what the same idea does in a real language. Treat both as checks on your own trace, never as a replacement for it.
If you want someone to watch your working and correct it as you go, see our online one-to-one Computer Science tuition. For the current notation rules and exam-year details, always confirm on the Cambridge syllabus page linked below.