PSLE Maths problem sums, and how to solve them
Problem sums carry most of the marks in Paper 2, and every one hides a trap. Your child needs to recognise which heuristic a question needs, draw it, and avoid the step that catches most children.
The 8 heuristics for PSLE problem sums
Model drawing (bar models)
Draw the quantities as bars to see the units and parts. The backbone of most P6 problem sums.
Before and after
Compare the situation before and after a change. Look for what stays the same: the total, one quantity, or the difference.
Constant difference
Ages and transfers between two people. The gap between them does not change, so it anchors the units.
Units and parts
Make the units of two ratios or fractions match before comparing them.
Working backwards
Start from the end amount and undo each step, in reverse order.
Supposition (assumption)
Suppose everything is one kind, such as all chickens, then correct the difference.
Guess and check
A sensible first guess, then adjust using a table. Accepted when the working is shown.
Patterns and listing
List the cases in order until the rule appears, then use it.
A problem sum, worked
Mr Tan is 32 years old and his son is 8. In how many years will Mr Tan be 3 times as old as his son?
- The difference in their ages never changes: 32 − 8 = 24 years.
- Later, Mr Tan is 3 units and his son is 1 unit, so the difference is 2 units.
- 2 units = 24, so 1 unit = 12. The son will be 12.
- 12 − 8 = 4 years.
Why 8 years is wrong: Dividing 24 by 3 treats the age difference as 3 units. When one person is 3 times the other, the difference is 2 units.
Problem sums by topic
Questions parents ask
What are PSLE Maths heuristics?
Problem-solving strategies taught in Singapore primary schools, such as model drawing, before and after, working backwards and supposition. Most Paper 2 structured questions need one or two of them.
Does my child have to draw a bar model in the PSLE?
No. Marks are given for any correct method that is clearly shown. A bar model is often the clearest way to show the working for fraction, ratio and age questions.
Why does my child understand the solution but cannot start the question?
Starting is the hard part: choosing the heuristic. Practising one kind of problem sum at a time, then mixing them, builds that judgement.
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