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P1 Units and parts

Today’s problem — free all day, every step. Every day has one.

compare centimetre lengths

Which is longer: 8 cm or 12 cm?

One step of the worked solution to compare centimetre lengths, drawn in pencil.
5 steps, drawn in pencil

See all 5 steps

MathBrush is being tested with a few parent groups, and every solution on the site is open to them — one household, all children. If you were given a code, it goes in once and this device remembers it.

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65 worked examples are free without a code, two from every pattern. No account, either way.

The pattern behind it: Units and parts

Cut one amount into equal shares. One number tells you what a share is worth.

In this one. Lengths in the same unit can be compared directly.

In allone share

How to spot it

A single amount is split by a ratio, a fraction or a percentage. One extra number gives you the leftover, the difference, or the value of one share.

Common mistake

Children match the given number to the wrong number of shares, using the whole bar when the number covers only the leftover or the difference between two people's shares.

Try one like it

Standard add in columns Use a written addition algorithm to calculate 46 + 35.
All 74 with this pattern →

The 33 problem patterns

All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.

A PDF, and a note when new solutions go up.