Fractions stop being just shaded shapes this year and start being numbers you can add, subtract and compare.
25 August 2026 · 5 min read
Fractions in Years 1 and 2 were mostly about recognising a half or a quarter of a shape or a group. Year 3 is where fractions become genuine numbers in their own right — things you can add, subtract, compare and order, not just spot on a diagram. It's one of the bigger conceptual jumps in the whole primary curriculum.
Year 3 addition and subtraction is deliberately limited to fractions that already share a denominator — 2/5 + 1/5, not 1/2 + 1/3. That's not an arbitrary restriction; it means a child can add the numerators directly (the number of parts) because the parts themselves are already the same size. Adding fractions with different denominators, which needs a common denominator first, doesn't arrive until Year 5 — so it's worth knowing that's genuinely later content, not something missing from Year 3.
Given 2/5 + 1/5, a very common early error is answering 3/10 — adding both the numerators and the denominators, as if a fraction were just two separate whole numbers stuck together. It's an entirely understandable mistake, since it applies ordinary addition logic to a form that doesn't work the same way. The fix isn't more repetition of the same type of question — it's going back to what the denominator actually represents: the size of each part, which doesn't change just because you're combining two amounts of that same-sized part.
Understanding that 1/2 and 2/4 are the same amount, even though the numbers look completely different, is a genuinely abstract idea for an eight-year-old. Physical fraction strips or bars — where a half-strip visibly lines up exactly with two quarter-strips — tend to do far more than an explanation on paper, because the equivalence becomes something a child can see and check for themselves, not just something they're told.
Cooking and sharing food are genuinely useful, low-pressure fraction practice: cutting a pizza into eighths and asking how many eighths make a quarter, or sharing a bar of chocolate between three people and talking through what fraction each person gets. The real-world context does a lot of the conceptual work that an abstract worksheet can't.
Grasp Maths checks a wrong fraction answer against known patterns like the "add the denominators too" misconception, so a mistake like 2/5 + 1/5 = 3/10 gets flagged for what it actually is — a specific, well-understood misunderstanding, not just a wrong mark.
Looking for printable practice too? See our Year 3 maths worksheets, or read the full Year 3 maths overview.
Try a free Grasp Maths practice session, matched to the Year 3 curriculum.