Converting units of measure – Year 3 maths lesson

Lesson 20 of 24 in the Year 3 maths course

UK version. UK school years, UK spelling and pounds (£). · US Math Department

A complete 45-minute lesson for Year 3 (ages 7–8) that runs on this page – at school or at home. Every answer is marked straight away, with a worked explanation.

Time: 45 minutes + 15 min homework
Year: Year 3 (ages 7–8)
You need: Paper, a pencil and this page
Marked: Instantly, with explanations

For parents: how to use this lesson

You don't need to know this topic yourself. The lesson explains each step on screen, one tidy step at a time. Every answer is marked straight away with a worked explanation, so you never have to mark anything.

Read what your child will learn and the big ideas together.
Press Start the lesson below and sit with your child for the teaching and the worked examples (about 19 minutes).
Let them do the practice on their own. They choose Getting started, On track or Challenge – start on On track and move up after a few right in a row.
Finish with the exit ticket and the talk question: “How do you decide whether to multiply or divide when converting?”
Later that day or the next day: the homework (15 minutes), then a practice test.

Watch out for

Dividing when you should multiply. Ask: will there be more of the smaller unit? Then multiply.
Using 100 for every conversion. Learn the facts: 1 km = 1,000 m, but 1 m = 100 cm.

Tip for home: Read food labels and convert grams to kilograms, or millilitres to litres.

What your child will learn

We are learning to convert between units of length, mass and capacity.

Success looks like

I know how metric units are linked.
I can convert between units.
I can solve problems with mixed units.

Key words

convert: change to a different unit
metric: units based on 10s: metres, grams, litres
kilo-: one thousand
centi-: one hundredth

What to have ready

Paper and a pencil
This page on a computer, tablet or phone
For the hands-on part: Measure things in centimetres and convert to metres, or weigh food in grams and convert to kilograms.

The big ideas (for the adult)

Metric units are linked by 10, 100 or 1,000: 1 m = 100 cm, 1 kg = 1,000 g, 1 litre = 1,000 ml.

From a bigger unit to a smaller unit, multiply: 3.5 kg = 3,500 g. From a smaller unit to a bigger unit, divide.

Before calculating with measures, make sure they are in the same unit.

The lesson, step by step

45 minutes in 5 parts
Part	Time	How it is checked
Starter: quick recall	5 min	Marked by Classfern
Teaching input	10 min	Not assessed, self-checked
Worked examples and guided practice	9 min	Not assessed, marked by Classfern
Independent practice	15 min	Marked by Classfern
Plenary and exit ticket	6 min	Marked by Classfern, self-checked

Starter, "your turn", practice and exit ticket are marked by Classfern. Worked examples and teaching are not assessed. The hands-on task and the reflection are self-assessed. Explanations in talk are judged by the parent and not recorded.

The lesson

It runs here on the page. No sign-up and no names – progress is kept only in this browser.

Homework and practice at home

15 minutes: 8 practice questions, 3 multiple-choice questions and 2 to remember from earlier work, then a short reflection. New questions every time, all marked instantly.

More practice

Year 3 measurement and money testMarked instantly

All Year 3 maths lessons and tests · Maths Department

Curriculum

National Curriculum for England, Year 3: “measure, compare, add and subtract: lengths (m/cm/mm); mass (kg/g); volume/capacity (l/ml)”

Contains public sector information licensed under the Open Government Licence v3.0.

Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board.