Today is rung 4 of 10 on this topic
Adding and subtracting fractions
Can do: Adds and subtracts fractions with the same denominator, and with related denominators like halves and quarters.
Why it matters
The commonest error in all of school maths lives here: adding the bottoms. It comes from never seeing what a denominator actually is.
What it looks like when it's wobbly
1/4 + 1/4 = 2/8. The child is adding two whole numbers because nothing has told them not to.
⏱️ Two-minute check
"1/4 + 1/4? And 3/4 − 1/2?"
Solid looks like: 1/2 (or 2/4) and 1/4, with the denominators left alone.
The full activity for this topic · 20 minutes
Fraction Strips Add Up
- 1Lay two quarter-strips end to end. Ask what the total looks like against the half-strip.
- 2Say the rule they can see: the pieces stay the same size, we just have more of them.
- 3Ask what 1/4 + 1/2 needs — swap the half for two quarters, physically.
- 4Now write the sums numerically, matching each step to a strip.
- 5Use a real one: half a cup plus a quarter cup while cooking.
If it's too hard
Same denominator only, with strips every time.
If it's too easy
Mixed numbers: 1 3/4 + 1/2, and subtraction that crosses a whole.
Say this
"The bottom number tells you the size of the piece. The pieces didn't get smaller — so why would the bottom change?"