These pages are the clean statement of an idea you have already met — in an exploration, in a warm-up, or in the twenty minutes you spent working out why somebody else’s program did that. The order below is the order the course needs them in. Come here after class, when you want the idea in one place and in plain words.

Unit 1 — Objects and the shape of a problem

Unit 2 — Data structures

Unit 3 — Algorithms and efficiency

Unit 4 — Building software together

Grade 11 asked whether your program works. This year the questions get harder and more interesting: does it model the problem honestly, can you defend the algorithm you chose, and can somebody else keep it alive after you have gone. Every page here ends with the curriculum expectations it serves, and nearly every one points at a practice set in Exercises and a complete working program in Programs.

Read the idea, then go build something with it — for somebody.