[In a diagram, three rectangular prisms marked a, b and c have their dimensions marked. The narrator reads out the onscreen text.]

NARRATOR: Question four. Find the volume of each of these rectangular prisms.

[Prism a is marked as 3 metres in height, width and breadth.]

NARRATOR: Part a. The area of a prism is given by the area of the base multiplied by the height. In this case, we could consider the base to be this 3-metre by 3-metre square. And therefore the height is 3 metres. So the area of the base is 3 times 3. And then we must also multiply by the height, which is also 3. Which gives a volume of 27 metres cubed.

[Prism b is marked as 2 centimetres by 4 centimetres by 1.5 centimetres.]

NARRATOR: Part b. Again, we consider the area of the prism as being the area of the base multiplied by the height. In this case I'm going to consider the base to be this rectangle with dimensions 2 centimetres by 1.5 centimetres. In which case, 4 centimetres becomes the height. So the area of the base is 2 times 1.5, and then I need to multiply by the height, which is 4. Giving 3 times 4, or 12 cubic centimetres.

[Prism c is marked as 15 millimetres by 6 millimetres by 12 millimetres.]

NARRATOR: Part c. Again, we consider the area of a prism to be the area of its base multiplied by its height. In this case I'm going to consider the base to be this 15 millimetre by 6 millimetre rectangle, which makes the height 12 millimetres. So the area of the base is given by 15 times 6, and then we need to multiply by the height, which is 12. 15 times 6 is 90, multiplied by 12, which gives 1080 cubic millimetres.