You will learn
- Name metric units of length, mass and capacity.
- Choose a sensible unit.
- Know the unit relationships.
- Estimate with benchmarks.
Version 0.2 · expanded edition · built from cited public sources Content is based on the official frameworks and sources listed under Sources and standards. No official endorsement is claimed. Written in the style of common primary school assessments. No exam result is promised.
Student lesson
- Length: mm, cm, m, km.
- Mass: g, kg.
- Capacity: mL, L.
- Pick a sensible unit by comparing with something you know.
Words to know
How long or far.
How heavy.
How much a container holds.
A unit everyone agrees on.
1. Discover: measuring things
A pencil, a bag of rice and a bottle of water: which units would you use for each?
2. Understand: metric units
- Length: mm, cm, m, km. 1 cm = 10 mm; 1 m = 100 cm; 1 km = 1,000 m.
- Mass: g, kg. 1 kg = 1,000 g.
- Capacity: mL, L. 1 L = 1,000 mL.
Benchmarks: a pencil is about 15 cm; a bag of rice about 1 kg; a water bottle about 1 L.
Idea 1: Choose a unit
An egg has a mass of about 60 grams. A pond might be 20 metres wide. A cup of tea is about 250 millilitres.
Idea 2: Relationships
1 m = 100 cm. 1 kg = 1,000 g. 1 L = 1,000 mL.
Idea 3: Benchmarks
A road is measured in km and a pencil in cm.
Why standard units? Everyone then gets the same measure.
3. Worked examples
Example 1 (I show you): Mass
An egg
- Small: grams.
Answer: g
Example 2 (We do it together): Length
A pond width
- Medium: metres.
Answer: m
Example 3 (You try): Capacity
A cup of tea
Show the steps and answer
- Small: millilitres.
Answer: mL
Did you know?
The metric system is based on powers of ten.
Why this matters
Standard units let people trade, build and cook the same way everywhere.
4. Explore: choose
You need a ruler, a bottle and a bag.
- Measure a pencil in cm.
- Find the capacity on a bottle.
- Check the mass on a packet.
- Match each with a unit.
Think about it: what did you notice?
cm, L, kg.
5. Practise
Say it in a sentence
Use these starters when you talk about the lesson. Say them out loud.
- I measure ___ with ___.
- 1 ___ = ___ ___.
- A sensible unit for ___ is ___.
- It is about ___.
Guided practice
Question 1. Unit for a road?
km.
Question 2. Unit for a pencil?
cm.
Question 3. Unit for a bag of rice?
kg.
Independent practice
Level 1: Start
- Unit for the mass of an egg
- Unit for a pond’s width
- Unit for a cup of tea
- 1 m = ___ cm
- 1 kg = ___ g
Level 2: Grow
- Unit for the capacity of a bottle
- Unit for the mass of a person
- Unit for the length of a classroom
Level 3: Stretch
- 1 km = ___ m
- Choose a unit for the mass of a pencil
- Ben says 1 kg = 100 g. What is wrong?
Answers are in the answer key below. Try first, then check.
6. Apply: everyday mathematics
Which unit would you use for the mass of a feather?
Show a sample answer
Grams.
Another one. Choose a sensible unit for the length of a football pitch and explain.
Show a sample answer
Metres, because a pitch is about 100 m long.
7. Common mistakes
Fix: Think about size.
Fix: Compare with a benchmark you know.
Fix: Ask: how long, how heavy or how much does it hold?
8. Lesson summary and revision card
- I can name metric units of length, mass and capacity.
- I can choose a sensible unit.
- I know the unit relationships.
- I can estimate with benchmarks.
9. Check and master
Answer all 14 questions. You will see feedback after each one.
Your result appears here after you answer every question.
10. Key takeaways
- Match unit to size.
- Know the relationships.
- Use benchmarks.
11. Next lesson
Next lesson: Unit conversions. Keep going with the next idea in this course.
Exam practice
These questions are written in the style of common school and international primary assessments. Try them on your own, without looking back. Then check your answers in the marking guide. The marks are shown in brackets.
- Which unit measures the mass of an egg? [1 mark]
- Which unit measures the width of a pond? Explain. [2 marks]
- Which unit measures a cup of tea? Explain. [2 marks]
- How many grams in 1 kg? [1 mark]
- Ali says a pencil is 15 m long. Is he right? Explain. [3 marks]
Total: 9 marks.
Marking guide and model answers
- Grams [1]
- It is a length [1]; metres [1]
- It is capacity [1]; millilitres [1]
- 1,000 [1]
- No [1]. 15 m is as long as a bus [1]. 15 cm is sensible [1].
Score guide: 8 to 9 = secure. 6 to 7 = nearly there, revise the parts you missed. Under 6 = work through the lesson again with a grown-up.
Printable worksheet
- 1 m = ___ cm
- 1 kg = ___ g
- 1 L = ___ mL
- 1 km = ___ m
- 1 cm = ___ mm
- The best unit for a road is
- The best unit for a pencil is
- 1 m =
- 1 kg =
- 1 L =
Homework
Find three items for each unit type at home.
Answer key and marking scheme
| Question | Expected response | Marks |
|---|---|---|
| 1 m = ___ cm | 100 | 2 |
| 1 kg = ___ g | 1,000 | 2 |
| 1 L = ___ mL | 1,000 | 2 |
| 1 km = ___ m | 1,000 | 2 |
| 1 cm = ___ mm | 10 | 2 |
| Total | 10 |
Practice answers: Worksheet: 1 100; 2 1,000; 3 1,000; 4 1,000; 5 10.
Quiz answers: 1 A, 2 B, 3 C, 4 A, 5 B, 6 A, 7 B, 8 C, 9 A, 10 B, 11 C, 12 A, Challenge 1 C, Challenge 2 C.
Extra worksheet answers (items 6 onward): 6 km; 7 cm; 8 100 cm; 9 1,000 g; 10 1,000 mL.
Independent practice answers. Level 1: 1 grams (g); 2 metres (m); 3 millilitres (mL); 4 100; 5 1,000. Level 2: 1 mL; 2 kg; 3 m. Level 3: 1 1,000; 2 g; 3 1 kg = 1,000 g..
Mastery and remediation
| Objective | Bronze (Developing) | Silver (Proficient) | Gold (Advanced) |
|---|---|---|---|
| O1 Name metric units of length, mass and capacity | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O2 Choose a sensible unit | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O3 Know the unit relationships | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
| O4 Estimate with benchmarks | Shows this with help from an adult or a picture | Does this independently and explains how they know | Explains it clearly and uses it in a new situation |
Courseversity badge thresholds (overall quiz score): Gold = 90–100%; Silver = 80–89.9%; Bronze = 70–79.9%. A badge is never a full record of progress.
If a learner struggles
- Find the misconception: Using a unit that does not fit. Think about size.
- Explain another way: use real objects first, then pictures.
- Show a simpler example: Measure objects with cm.
- Guided practice: work through one example together and let the learner try the next one.
- Reassess: use the quiz again or the worksheet.
- Move on when the learner shows Silver-level evidence independently.
For parents and guardians
In this lesson your child chooses sensible metric units for length, mass and capacity. You do not need to be good at mathematics to help.
- Weigh and measure kitchen items.
- Ask: how long, how heavy or how much?
- Compare with a ruler, a litre bottle and a kilo of sugar.
- Ask “how do you know?” after each answer, and listen.
- Praise effort, not only right answers. Mistakes are how we learn.
- Ten to fifteen minutes a day is better than one long session.
Teacher package
1–5. Objectives, prerequisites, materials, preparation, duration
Lesson objectives. Learners will: name metric units of length, mass and capacity; choose a sensible unit; know the unit relationships; estimate with benchmarks.
Prerequisite knowledge. Grade 3 measurement.
Materials. Counters (stones, seeds or bottle tops), paper, pencils, board or chalkboard. Low-resource options: use stones, seeds, sticks, bottle tops or drawings in the sand or on the board instead of printed materials.
Preparation. Gather the counters and draw the example pictures on the board before the lesson.
Suggested duration. 45–60 minutes. It can be split into two shorter sessions.
6–9. Teaching procedure, explanation notes, guided and independent activities
Introduction (5 min). Start with the Discover situation and let learners suggest ideas before you teach.
Explanation (10 min). Teach the Understand section with real objects first, then pictures, then symbols and words.
Guided activity (10 min). You need a ruler, a bottle and a bag. Learners follow the Explore steps in pairs.
Independent activity (10 min). Learners complete the independent practice and the worksheet.
Assessment and reflection (5 min). Ask each learner to say one thing they learned and how they know it.
Key questions. What am I measuring? Which unit is sensible?
Teacher explanation notes. Use the concrete, pictorial, abstract order: real objects first, then pictures, then symbols and words. Return to real objects whenever a learner needs support.
10–12. Differentiation, formative assessment, common misconceptions
Support. Use real objects and work with a partner; say each step aloud together. Extension. Ask learners to make up their own example and explain it to a partner.
Formative assessment. Listen to learner explanations, ask “how do you know?”, and check the independent work.
Misconceptions. Using a unit that does not fit. Think about size.
13–15. Assessment questions, answer keys, marking scheme
Use the quiz and worksheet on this page. The 9-mark exam practice scheme, the 10-mark scheme and all answers are in the answer sections above. Re-check every answer and the marking scheme before publication.
16–19. Remediation, enrichment, homework, teacher reflection
Remediation. Measure objects with cm. Enrichment. Invite learners to find or create three more examples at home or in the classroom and explain them. Homework. See above.
Teacher reflection. After teaching, record: which concepts learners understood; which misconceptions occurred; which activities worked; which learners need more practice; and what to improve next time.
Sources and standards
This lesson is based on the sources below, and no official endorsement is claimed. Reference starting points named in the Courseversity standard: Common Core State Standards for Mathematics, Cambridge Primary and the IB Primary Years Programme. Where a standard code is named, it points to the official framework.
Official standards for this topic area. Common Core State Standards for Mathematics (official site): Grade 4 » Measurement & Data. These pages list the standards that cover this topic area; read them alongside the lesson.
Research used to shape this lesson. Common Core 4.MD.A.1; Cambridge Primary Mathematics Stage 4 (metric units). These sources informed the lesson.