Grade 4 Mathematics Measurement – Volume Notes

Mathematics — Measurement

Subtopic: Volume (for age 9)

What is volume? Volume tells us how much space is inside a solid object (for example a box) or how much liquid a container can hold.

1. Unit used for volume

• Small solids: cubic centimetres (written cm³) — imagine a cube that is 1 cm on each side. That is 1 cm³.
• Liquids and bigger containers: litres (L) and millilitres (mL). 1 cm³ = 1 mL.
• Useful conversions:
  • 1000 cm³ = 1 L
  • 1000 L = 1 m³ (one cubic metre)
  • So 1 m³ = 1,000,000 cm³

2. How we find volume of a box (rectangular prism)

If you have a box with length, width and height (all in cm), the volume is:

Volume = length × width × height

The answer will be in cubic units (for example cm³).

3. Picture: unit cubes and layers

Imagine small 1 cm × 1 cm × 1 cm cubes. A box that is 3 cm long, 2 cm wide and 2 cm high has how many of these cubes?

4. Worked examples

Example 1

A small box is 10 cm long, 5 cm wide and 4 cm high. What is its volume?

Volume = 10 × 5 × 4 = 200 cm³

Example 2 (liquid)

A water tank holds 2000 cm³. How many litres of water can it hold?

Since 1000 cm³ = 1 L, 2000 cm³ = 2 L.

5. How to measure volume in the classroom

• Count unit cubes if the object is made from small cubes.
• Use a ruler to measure length, width and height (in cm) and use Volume = L × W × H.
• For liquids, use a measuring jug or a container marked in litres or millilitres.

6. Practice questions

1. A box measures 8 cm by 3 cm by 2 cm. Find its volume (cm³).
2. A jug holds 1500 cm³ of water. How many litres is that?
3. A crate is 2 m long, 0.5 m wide and 0.4 m high. Find its volume in cubic metres and in litres. (Hint: 1 m = 100 cm ; 1 m³ = 1000 L)

7. Answers

1. 8 × 3 × 2 = 48 cm³
2. 1500 cm³ = 1.5 L
3. Volume = 2 × 0.5 × 0.4 = 0.4 m³. In litres: 0.4 m³ × 1000 = 400 L.

Tip: Always write the unit (cm³, L or m³) with your answer — units tell us what the number means.