Primary 5 covers multiplying a proper fraction by a proper or improper fraction, multiplying two improper fractions, and multiplying a mixed number by a whole number, without a calculator.
What the four operations with fractions actually asks of a Primary 5 student
Multiplying fractions is procedurally easier than adding them — multiply across, no common denominator needed — which surprises children who expect it to be harder.
The conceptual difficulty is that multiplying can now make things smaller. Half of a half is a quarter, and that contradicts every previous experience of multiplication.
Mixed numbers must be converted to improper fractions first. Multiplying the whole parts and the fraction parts separately is the classic wrong method.
What the syllabus covers
Under the MOE primary mathematics syllabus, the four operations with fractions at Primary 5 covers:
- multiplying a proper fraction and a proper or improper fraction
- multiplying two improper fractions
- multiplying a mixed number and a whole number
Where the marks actually go
Multiplying mixed numbers without converting first, which gives an answer that is too small and looks plausible.
Finding a common denominator out of habit, which is unnecessary and introduces errors.
Not simplifying, either during the calculation where it would help, or at the end where it is required.
How to practise this properly
Convert every mixed number to an improper fraction before doing anything else, as a fixed first step.
Simplify before multiplying where a numerator and denominator share a factor. It keeps the numbers small and reduces slips.
Sanity-check the size: multiplying by a fraction less than one must give a smaller answer.
Say “of” instead of “times” when a fraction multiplies a whole number. Two thirds of nine is immediately meaningful in a way that 2/3 × 9 is not.
What this leads to
Primary 6 divides by fractions, which is defined in terms of multiplication. Fluency here is what makes that manageable.
This is why we teach the primary years as one arc rather than six separate ones. Our MOE-aligned curriculum runs from Primary 1 to Primary 6, so when something goes wrong we can trace it to the year it actually formed and repair it there, instead of drilling the level where it happens to be showing up. That distinction usually decides whether extra work produces improvement or simply produces more work.
What lessons at Odyssey are actually like
Our students describe the teaching in their own words. This one is a secondary student — the approach is the same one your child would meet in a primary class, taught at the right level. More are on Odyssey Math TV.
Getting help with this topic
We teach Primary 5 maths in small classes at Hexacube, 160 Changi Road #01-02, about three minutes from Eunos MRT. You can see our class schedules and fees, read about our math tutors, or look through the primary school math tuition programme as a whole. If your child is in a nearby school, our primary school directory may be useful too.
The first lesson is a free trial, and it is a diagnosis rather than a sales pitch: we would rather tell you what is actually wrong than sign you up. If the answer is that your child does not need tuition yet, we will say so. Book a free trial class or WhatsApp +65 8512 6882.
What we describe here comes from teaching this syllabus in our own classes since 2012. It is not a forecast for any individual child: progress is produced jointly, by a student willing to do the work with support at home. We do not promise grades. Topics follow the MOE primary mathematics syllabus — check the current syllabus on the MOE website for the definitive version, and see our curriculum page for how we teach it.
Frequently asked questions
Do you need a common denominator to multiply fractions?
No. Multiply the numerators and multiply the denominators. Common denominators are only needed for addition and subtraction.
How are mixed numbers multiplied?
Convert to improper fractions first, then multiply. Handling whole and fraction parts separately does not work.
Why does multiplying make the answer smaller?
Because multiplying by a fraction less than one takes a part of the number. Half of eight is four, and that is what × 1/2 means.
Should the answer be simplified?
Yes, and simplifying before multiplying usually makes the arithmetic easier as well.
