KS2 SATs 2017 — Maths Papers 2 & 3: Reasoning

The idea

A bar model is a picture of a problem. Draw one long bar for the whole amount, then split it into boxes for the parts. If you know the whole and one part, the missing part is whatever is left. If you know the parts, the whole is their total.

Bar models are especially helpful for comparison problems. Draw two bars, one above the other: a longer bar for the bigger amount and a shorter bar for the smaller amount. The extra piece of the longer bar is the difference, and seeing it makes the subtraction obvious.

Equal parts are shown as equal boxes. If a bar is split into four matching boxes and you know the whole, dividing by four finds each part. Draw the model first, then write the calculation it shows you.

Worked example

Nina has 58 stickers. She has 17 more stickers than Ben. How many stickers does Ben have?

1. Draw Nina's bar as the longer bar, worth 58.
2. Ben's bar sits below it, shorter by a piece worth 17, because Nina has 17 more.
3. Ben's bar matches Nina's bar with 17 removed: 58 − 17 = 41.

Answer: 41 stickers

Watch out

• Adding 17 because the word 'more' appears, instead of checking who has more.
• Drawing parts that are not equal when the problem says they are shared equally.