WombatMaths
All Year 4 topics

Measurement · Length

Length and its units

Choose sensible units (mm, cm, m, km) and convert between metres and centimetres.

Victorian Curriculum VC2M4M01 · 60 questions · 2 step-by-step

How we teach it

This is what sits under the answer sheets in the app — the same cards, clips and lessons your child sees after a question.

More lessons for this topic are on the way.

One question, as your child sees it

And the answer sheet that follows a second wrong try: what we know, what we need, the steps, a check, the answer.

Amara drew a line 65 mm long. Tessa's line is twice as long, and Willa's line is 25 mm shorter than Tessa's.
What is the length of Willa's line, in centimetres?

Your child types the answer on a number pad.

First hint: Find Tessa's line first, take 25 mm off it, and only then change to centimetres. Write your answer as a decimal if it needs one, the way 75 mm would be written 7.5 cm.

The answer sheet

Do the millimetres first and change to centimetres last, or the numbers get muddled.

Amara's line is 65 mm.

Tessa's is TWICE as long: 65 × 2 = 130 mm.

Willa's is 25 mm SHORTER than Tessa's: 130 − 25 = 105 mm.

now change to centimetres. 10 mm make 1 cm, so 105 mm = 10.5 cm.

The question asks for centimetres, so an answer of 105 is the right length written in the wrong unit.

Start practising — free