154
Volume of shapes
Textbook: Part 4, lesson 144, pp. 60–61
GoalVolume of shapes: litres and cubic centimetres; finding the volume of a cuboid by layers.
New words
volume · hajmlitre · litrcubic centimetre (cm³) · kub santimetr (sm³)layer · qatlam
Explanation
Volume shows how much space a shape takes up. The volume of a liquid is measured in litres, of a solid in cubic centimetres (cm³): 1 cm³ is a little cube with edge 1 cm. A box 12 cm long, 4 cm wide and 2 cm high holds 12 × 4 = 48 little cubes in one layer, 2 layers – 48 × 2 = 96 cubes. So its volume is 96 cm³. Volume = length × width × height.
Worked examples
A cube with edge 3 cm: 3 × 3 × 3 = 27 cm³.
25 cans × 3 L = 75 L and 12 cans × 2 L = 24 L; in all 99 L.
Class activity
“A box from cubes”: children build a 4 × 3 × 2 shape from 1 cm cubes. They lay the first layer (4 × 3), then the second, count all the cubes and state the volume.
Practice
1
A box is 12 cm long, 4 cm wide and 2 cm high. How many 1 cm cubes fit in it?
96
2
How many cubes fit on the bottom of the box (12 cm by 4 cm)?
48
3
A juice box has a square bottom with side 7 cm and is 20 cm high. What is its volume in cm³?
980
4
A shop received 25 cans of apple juice of 3 L and 12 cans of pear juice of 2 L. How many litres of juice came in total?
99