Session 1 · SOLVE: Link Ideas
Crack it, then make it
- 15 minFrequency analysis: decode a longer message with an unknown shift by counting which letter appears most. In English it is usually E. Read 'Secret codes: from Caesar to your phone'.
- 25 minIn groups, design one lock each: a prime or factor lock, a power or root lock, an integer lock, an order-of-operations lock, and the final cipher. Write the puzzle card, the answer and a hint card.
- 10 minTohu asks one question about your puzzle: how do you know there is only one answer?
Session 2 · SOLVE: Verify
Test run: break each other's locks
- 10 minSwap puzzles with another group. Rules: no help from the makers, the makers only watch and record.
- 30 minSolve and record for each lock: solved, solved with hint, stuck, or found a different answer. Time each lock.
- 10 minDebrief: for any lock with two answers or none, find the flaw. Was it the maths, the wording or the clue?
Getting started
Use a template puzzle card with a sentence starter and a one-step question for the first lock.
Stretch
Make a two-layer lock: the answer to one puzzle is the shift for the cipher in the next.
Checkpoint
Every lock has been tried by another group and its results table shows what needs fixing.
Activities for this week
- Build and test an escape-room lock: Does our puzzle have exactly one answer, and can someone else find it?
Useful this week
- Positive and negative numbers ↗ Adding and subtracting across zero, shown on a number line.
- Otago region: climate, plants and animals ↗ Where New Zealand's record low temperature of −25.6°C was measured.
- CS Unplugged topics ↗ New Zealand-made activities on binary, codes and error detection without computers.
- Order of operations ↗ Check each lock's calculation follows the agreed order.