GCSE Computer Science
Free GCSE Computer Science resources
Everything here is free, no login required. Each resource explains a concept from the GCSE Computer Science specification, shows worked examples you can run in the browser, and links to the relevant Python Coach tool.
Python for loops — GCSE Computer Science
How for loops work, how range() counts, and what examiners actually test. Includes a worked example you can run and modify.
See how range() actually counts →Python functions — GCSE Computer Science
What functions are for, how parameters and return values work, and why the print vs return distinction costs students marks.
See why print isn't the same as return →Binary and hexadecimal — GCSE Computer Science
How binary place values work, how hex maps to binary, and how to approach conversion questions on the mark scheme.
Convert binary and hex step by step →Python Turtle graphics — GCSE Computer Science
How Turtle graphics makes loops and functions visible, with worked examples showing squares, hexagons, and parametrised shapes.
Draw shapes with loops and functions →Python trace tables — GCSE Computer Science
How to complete a trace table line by line, with worked examples covering variable swapping and loop accumulation.
Learn to trace code line by line →Python while loops — GCSE Computer Science
How while loops differ from for loops, the input validation pattern, and what examiners test.
See when to use while instead of for →Python lists — GCSE Computer Science
How to create, index, and iterate through lists — and why zero-indexing catches students out.
See why indexing starts at zero →Python variables and data types — GCSE Computer Science
What variables store, the four main data types, and why type casting matters in exam answers.
See why type casting trips students up →Python strings — GCSE Computer Science
Length, indexing, substrings, and concatenation — the string operations tested on every exam board.
See how slicing and indexing work →Python selection — if statements — GCSE Computer Science
How if, elif, and else work, why the order of conditions matters, and how logical operators combine them.
See how elif order changes the output →Python bubble sort — GCSE Computer Science
The pass-by-pass comparison mechanism, a worked Python implementation, and how many passes a sort actually needs.
See how the passes work →Linear and binary search — GCSE Computer Science
How linear search and binary search work, when to use which, and why binary search needs sorted data.
Compare linear and binary search →Python file handling — GCSE Computer Science
Opening, reading, and writing files with open(), the with open() pattern, and why 'w' mode isn't the same as 'a'.
See the open/read/write pattern →Python subroutines — procedures and functions — GCSE Computer Science
The procedure vs function distinction, parameters and arguments, and local vs global scope.
Understand procedures vs functions →Python 2D lists — GCSE Computer Science
How 2D lists represent a grid, indexing with two indices, and iterating with nested loops.
See how indexing works →Pseudocode in GCSE Computer Science exams
The pseudocode constructs used across AQA, OCR, and Edexcel, and how to write answers that actually get marks.
Read exam pseudocode with confidence →Python error types — GCSE Computer Science
Syntax, runtime, and logic errors — what each one looks like, and how to tell them apart under exam conditions.
Tell the three error types apart →Python string methods — GCSE Computer Science
split(), find(), count(), ord() and chr() — the string methods that appear as their own mark-scheme questions.
See what each method returns →Python type casting — GCSE Computer Science
int(), float(), str(), bool(), and why int(3.9) truncates to 3 instead of rounding to 4.
See why casting isn't rounding →Python random numbers — GCSE Computer Science
random.randint() and random.random(), with a dice simulator and a random-choice worked example.
Build a dice simulator →Python operators — GCSE Computer Science
Arithmetic, comparison, logical and assignment operators — including how // and % map to DIV and MOD.
See how DIV and MOD map to Python →Python arrays and lists — GCSE Computer Science
Why the spec says "array" but Python uses lists, and how to bridge the terminology in exam answers.
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