1. WALT: Express missing number problems algebraically

2. Starter Think of pairs of numbers with a product of 48
Write equalities to show equivalence, e.g. 12 × 4 = 6 × 8.
Repeat for divisions with answers of 4, e.g. 12 ÷ 3 = 40 ÷ 10.

3. 25 + a = 30 This is an equation. ‘a’ stands for a mystery number.
What is a?

4. 25 + a = 30 30 25 a

5. 6b = 42
6b stands for 6 x b
What is b?

6. If 6 times something is 42, then the something must be 7.
6b stands for 6 x b
What is b?
If 6 times something is 42, then the something must be 7. 42 b b b b b b

7. 35 ÷ c = 7

8. 35 ÷ c = 7
C = 5

9. 3 × 5 = 17 – d
Discuss with your partner how you might work this one out.

10. 3 × 5 = 17 – d
Discuss with your partner how you might work this one out.
15 equals 17 minus something, so the something must be 2.
15 = 17 – d

11. 3e + 1 = 18 – 5

12. Now...
work in pairs to write their own missing number problem for another pair to solve.

13. Plenary
What are the values of a, b and c? X 3 b a 21 56 c 12 32