Repeat Yourself

Loops shrink programs

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• A loop runs its body a fixed number of times.
• Nested loops multiply: 4 repeats of 5 repeats is 20.
• Find the repeating pattern first, then wrap it in a loop.

Steps

1. Loops
2. A long corridor
3. Climbing the stairs
4. Counting moves
5. Loops inside loops
6. Around the block
7. The long zigzag