Math lesson plan · 3rd grade (Year 4 in England) · 45 minutes
Millimetres, centimetres and metres
Measurement
CCSS 4.MD.A.1England: Y3 Measurement
Objective and success criteria
Students will: Millimetres, centimetres and metres.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Measure in cm, m, inches and feet
Leads to: Convert metric lengths: km, m, cm and mm
Materials: Rulers, scales and measuring jugs, Clock faces, Conversion chart, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Measure in cm, m, inches and feet). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What is the best estimate for the length of a door? (20 m / 200 m / 2 cm / 2 m) → 2 mPrompt: A centimetre is about the width of a finger nail.
- What is the best estimate for the length of a bus? (1200 m / 12 m / 120 m / 12 cm) → 12 mPrompt: A centimetre is about the width of a finger nail.
- What is the best estimate for the length of a book? (250 cm / 25 cm / 25 m / 2500 cm) → 25 cmPrompt: A centimetre is about the width of a finger nail.
Hook · 5 min
- Ask the class to estimate the length of the room or the weight of a bag before measuring it.
- Share the objective: Millimetres, centimetres and metres. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: 60 mm = ? cm
- Step 1: 60 mm = 6 cm
- Answer: 6
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- 8 m = ? cm → 800Prompt: 1 cm = 10 mm and 1 m = 100 cm.
- A young tree is 2 m 83 cm tall. How tall is it in centimetres? → 283Prompt: 1 m = 100 cm.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Which is longer: 50 mm or 3 cm? (50 mm / 3 cm / They are equal) → 50 mmPrompt: Change both to millimetres.
- A young tree is 1 m 44 cm tall. How tall is it in centimetres? → 144Prompt: 1 m = 100 cm.
Watch out for
- Measuring from the end of the ruler instead of zero.
- Converting units the wrong way (multiplying instead of dividing).
Support and stretch
Support
- Review first: Measure in cm, m, inches and feet.
- Use concrete materials: rulers, scales and measuring jugs.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Convert metric lengths: km, m, cm and mm.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-3.
Free lesson plan from eurekami.com/lesson-plan-builder