Level 1 · Ages 6–8
Read it again any time, including while you work through the exercises.
Look around you: a playing die, a cereal box, a ball, a tin can. All these objects have volume, you can hold them in your hand and turn them around. In geometry, we call them solids. Unlike the flat shapes you drew on paper, a solid takes up space.
The cube is the shape of a die: all its faces are identical squares, and it has 6 of them. The rectangular box (cuboid) looks like a shoebox: its faces are rectangles. Place a cube or a box on the table and it sits still, thanks to its flat faces.
The ball is completely round, like a balloon or a marble: it has no flat face, no corner, and it rolls in every direction. The cylinder mixes both worlds: a tin can has two flat round faces (discs) and one curved surface. Lying down, it rolls; standing up, it stays put.
To recognise a solid, ask yourself three questions: does it roll? Does it have flat faces? Are its faces squares, rectangles or discs? With these three clues, you will become a true solid detective. Your turn!
Lucas is holding a cereal box. Which solid is it?
Roule ? Non
First I test it: the box does not roll, it has flat faces everywhere. So it is neither a ball nor a cylinder.
6 faces
I count the faces: one at the front, one at the back, one on top, one underneath, one on the left, one on the right. That makes 6 faces.
Faces = rectangles
I look at the shape of the faces: they are long rectangles, not identical squares. So it is not a cube.
Result: The cereal box is a rectangular box (cuboid).