KS3 Algorithms Lesson — Flowcharts, Sequence, Selection and Iteration

A complete KS3 computing lesson on algorithms and flowcharts — the three building blocks, the four flowchart symbols, a flowchart to trace, one to write, and an extension that puts two algorithms for the same job side by side.

Teachable by a non-specialist. The explanation pages can be read aloud or projected as they are, the subject knowledge is in the teacher notes rather than assumed, and every task has a worked answer.

Included (print PDF + fully editable PowerPoint, 10 pages):

• Teacher notes with the subject knowledge in one box, plus the three misconceptions that actually come up — decisions that are not yes/no, loops that never end, and “an algorithm is a computer thing”
• Starter, explanation, and the four flowchart symbols with what each one is for
• A worked example, a trace-it-three-times table and a find-the-fault task
• Trace task — a flowchart with a loop, and a trace table to complete
• Write-your-own — a cash machine, with a core version and a stretch version that allows three PIN attempts
• Extension: linear search against binary search, with a worst-case table to fill in
• Exit-ticket plenary, full worked answers, and a scaffolded support version

Clear layout, generous spacing and dyslexia-aware design throughout, following British Dyslexia Association style guidance.

Curriculum: KS3 computing — “understand several key algorithms that reflect computational thinking; use logical reasoning to compare the utility of alternative algorithms for the same problem”.