Success criteria
- I can connect decimal multiplication to whole-number multiplication in cents.
- I can divide a money amount and interpret leftover cents.
- I can reject an answer whose size does not fit the situation.
Explain
Six tickets at HK$3.75 can be treated as 375 cents × 6, then converted back once. Explain why multiplying by 6 should produce an answer larger than HK$3.75 but smaller than HK$30.
Independent practice
Six tickets cost HK$3.75 each. What is the total?
Split HK$25.99 among four people using whole cents. What equal share can each person pay? Enter the amount in HK dollars and cents.
How many cents remain after that equal split?
Which statement correctly describes the split?
Whole cents cannot be divided into smaller currency units.
Transfer
Design a bill split for three people when one person ordered an extra HK$12.50 item. Show a fair rule, calculate it, and explain why “divide the whole bill equally” may not fit the context.
Delayed check
One week later, solve 7 × HK$4.25 and split HK$31.01 among five people. State both each share and any remainder.
Evidence and next step
Add the annotated bill split and delayed check to jeremy/portfolio/math/unit-1/decimal-operations.md.
- Secure on both days + clear reasonableness explanation → Unit 1 core is ready for review; consider the stretch gate.
- Arithmetic secure but remainder misunderstood → practise two physical coin splits.
- Multiplication error → return to cents and an area/partial-products model.