From P3 to P4 Maths: What Actually Changes

27 September 2026 · by Larry

A child who finished P3 comfortably can open a P4 maths book in the first week of the new year and look genuinely lost — not on a hard question, but on a page of words they have never seen before. Factors. Multiples. Decimal point. Nobody explained that these were coming, because from where a parent sits, nothing "harder" seems to have happened yet.

That is the real difference between this jump and the one the year before. Going from P2 to P3 is mostly the same ideas arriving in longer, trickier sentences. Going from P3 to P4 is different: two topics show up that simply did not exist last year, and a few others that felt finished turn out not to be.

1. Two brand-new topics land in the same term

Factors and multiples appear for the first time in P4, and so do decimals. Neither is a harder version of something from P3 — they are new ways of thinking about numbers that a child has never been asked to do before.

Factors and multiples ask a child to think about a number's relationships rather than its value: what divides into it exactly, and what it divides into. That is a genuinely different question from "what is 6 times 7", and the two words are also easy to swap, which is its own separate trap — see why children swap them, and how to check.

Decimals ask a child to unlearn a rule that has been reliable for three years: that more digits means a bigger number. It doesn't, once there's a decimal point involved, and that single reversal is behind most of the mistakes children make with them — laid out in decimals: the four slips, and a two-minute check.

Because both arrive at once, a child can be building two new mental pictures in the same few weeks, on top of everything from P3 they are still expected to keep using. That is plenty of reason for a paper to come home looking worse, with nothing actually wrong.

2. Fractions stop being simple

P3 fractions mostly compare or combine pieces that are already cut the same size — halves with halves, quarters with quarters. P4 asks a child to add and compare fractions with different denominators, which means finding a common one first, before any of the actual adding can happen.

That extra step is easy to miss the point of. A child can know perfectly well that a half is bigger than a quarter and still have no idea what to do with a half plus a third, because the method they built in P3 — "just look at the pieces" — doesn't work once the pieces are different sizes. It needs a genuinely new tool: finding an equivalent fraction, which is really the multiples idea from above, just used for a different job.

3. Shapes need a tool now, not just an eye

Up to P3, angles are mostly something to spot — is this one bigger than a right angle, smaller, or about the same. In P4, a child is expected to actually measure one, in degrees, with a protractor.

That's a small object to learn to use well: lining up the base line, reading the correct one of the two scales printed on it, and not just guessing from the picture. A child who has never practised with one will genuinely struggle at first, and it looks nothing like a maths difficulty — it looks like clumsiness with equipment, because that's exactly what it is, briefly.

4. Working still has to show, and now there's more of it

None of the above replaces what P3 already asked for — showing the steps, not just the answer. It's worth saying again here because a child juggling two new topics is exactly the child most likely to skip writing things down to save time, which is the opposite of what actually helps when a method is still new. If that habit was already shaky, the right answer but the marks still went is worth reading alongside this one.

How to tell which one you are dealing with

Take a question they got wrong and ask them to explain it back to you, out loud, without solving it again.

• They can't say what a factor or a multiple even means here. That's not carelessness — it's a brand-new idea that hasn't settled yet. Go back to the picture, not more questions.
• They read 0.35 as bigger than 0.5, or line the digits up on the wrong edge. That's the decimal reversal, and no amount of "be more careful" touches it — it needs the place-value picture rebuilt.
• They add fractions by adding the top numbers and the bottom numbers separately. That's the old same-denominator method being used where it no longer applies — a sign the common-denominator step was never really understood, just skipped.
• They can explain the idea but the answer is still off. Now it's an arithmetic slip, and it's the smallest of the four problems even though it's the one that shows up first on the page.

What helps, in order

Separate the new ideas from everything else, for a week. Don't mix a factors worksheet in with a general revision paper. A brand-new idea needs its own quiet space to form before it gets tested alongside four other things.

Use real, physical things for factors and multiples before the abstract version. Twelve counters arranged into rows — 1 row of 12, 2 of 6, 3 of 4 — makes "factor" a shape you can see, not a word to memorise.

Put decimals next to money, out loud. $0.35 and $0.50 are already completely intuitive to a child who has handled coins. The bridge from there to 0.35 and 0.5 on a worksheet is short, but it has to be built on purpose — it doesn't happen by itself.

Practise the protractor on its own, away from any actual maths question. Ten minutes measuring angles drawn just for practice, with nothing to calculate, removes the equipment problem so it stops disguising itself as a maths problem later.

Let the common-denominator step be slow, on purpose, for now. Speed comes once the method is solid. Rushing a fraction method that hasn't set yet is how a child ends up practising the wrong shortcut instead of the right one.

Three things not to do

• Don't treat all the wrong answers the same. A factors mistake, a decimal mistake and a fractions mistake need three different conversations, not one longer worksheet.
• Don't skip past the protractor because it feels like a small thing. A child who can't use the tool will look like they don't understand angles, when actually they just haven't held one enough yet.
• Don't judge this term against last term's marks. Two brand-new topics landing together is, on its own, a completely ordinary reason for a paper to look worse than the one before it.

The thing worth saying out loud

A child who was doing fine a few weeks ago and suddenly isn't will often draw the fastest, least accurate conclusion available: that they've gotten worse at maths, or were never as good as they thought. It's worth naming plainly what actually happened instead — two ideas they'd never met before arrived at the same time, and everyone needs a run at something new before it feels ordinary. If that conversation is already happening in your house, when your child says they are bad at maths takes it further.

There's a second jump the following year that catches a different child in a different way — see what changes between P4 and P5.