Here is a small box built from little cubes. Roughly how many cubes do you think are hidden inside it? Have a guess before we count.

Look at three cuboids on screen, each already filled with unit cubes. For each one, look at the bottom layer first: how many cubes cover the floor of the box? Then count how many layers are stacked on top. The volume is the cubes in one layer times the number of layers.

This next box has every side the same length. Be ready to say how the base and the layers work when the box is a perfect cube.

Together we build and read three cuboids on the shape-measurer. First we do 3 × 2 × 2. Next we do 4 × 4 × 4. Last of all we do 10 × 10 × 10. One pupil at a time sets each cuboid on the board while everyone watches. As a class we call out the bottom layer, then how many layers, then check the volume against the screen. The last box is worth a good look.

Build each cuboid from your cubes to match the volume called out, then we check by counting the cubes together. Build a box with volume 12 cm³, then 24 cm³, then 36 cm³. If you have no cubes at your desk, work out the length, width and height in your head and predict them out loud when a build goes up on the board. For the stretch: build a box with volume 24 cm³ that uses the most cubes on the bottom layer.