Length, Weight and Capacity in Daily Life: Class 3 Study Guide
We measure how long, how heavy and how much a container holds. India uses the metric system.
India uses the metric system. We measure length in centimetres (cm), metres (m) and kilometres (km), weight (mass) in grams (g) and kilograms (kg), and capacity in millilitres (mL) and litres (L).
Choosing a sensible unit matters. A pencil is about 15 cm long, a classroom about 8 m, and the distance between two cities is measured in km.
Units and how they link
| Measures | Small unit | Big unit | Link |
|---|---|---|---|
| Length | centimetre (cm) | metre (m) | 100 cm = 1 m |
| Length | metre (m) | kilometre (km) | 1000 m = 1 km |
| Weight | gram (g) | kilogram (kg) | 1000 g = 1 kg |
| Capacity | millilitre (mL) | litre (L) | 1000 mL = 1 L |
In the market and kitchen
We buy rice, dal and sugar in kilograms. Half a kilogram is 500 g and a quarter is 250 g. Milk is sold in litres or half-litres. A small glass holds about 200 mL. Vegetables are weighed on a scale, and a cloth is measured in metres.
Length, weight or capacity?
Small things, small units.
Use 100 or 1000.
A number needs a unit.
Adding and comparing
Always change both to the same unit before adding. 2 kg 300 g + 1 kg 700 g = 3 kg 1000 g = 4 kg. And 2 m 50 cm = 250 cm.
Worked examples and common mistakes
Example: A bag of rice weighs 5 kg. How many grams is that? 5 × 1000 = 5000 g. Example: A jug holds 2 L. Five glasses of 200 mL use 1000 mL, which is 1 L, so 1 L is left. Common mistakes: adding numbers with different units, and mixing up grams and kilograms. Look at the unit before you answer.
Check your understanding: model answers
1. 3000 g. 2. Kilometres. 3. 4 glasses, because 4 × 250 = 1000.
✨ Key Takeaways
- Use cm, m and km for length.
- Use g and kg for weight, and mL and L for capacity.
- 100 cm = 1 m; 1000 m = 1 km; 1000 g = 1 kg; 1000 mL = 1 L.
- Change to the same unit before adding.
💬 Questions for Discussion & Reflection
- How many grams are in 3 kg?
- Which unit would you use to measure a road?
- A bottle holds 1 L. How many 250 mL glasses can it fill?