3
Sorting, rolling and stacking
Learner’s Book 1: Unit 2, pp. 39–40
GoalName a cube, a sphere and a cylinder, even when it is turned, and say which shapes roll and which shapes can be stacked.
New words
sort · put things into groups that are alikeroll · turn over and overstack · put on top of each other
Explanation
Shapes that are the same have the same name, even if they have a different colour or size. A cube is still a cube when you turn it. A cylinder lying down is still a cylinder. We can sort shapes into groups: all the cubes, all the spheres and all the cylinders. Some shapes roll. A sphere rolls in every direction. A cylinder rolls when it lies on its curved side. Shapes with flat faces can be stacked. Can you stack spheres? They roll off!
| roll | stack |
|---|---|
| sphere, and a cylinder on its side | cube, and a cylinder standing up |
Worked examples
A red box and a green box are both cubes, even if they are different colours. We sort them into the same group.
A ball is a sphere. When we put it on a slope, it rolls down.
Boxes shaped like cubes can be stacked: put one on top of the other. A tin standing up can be stacked too.
Class activity
Roll and stack: collect a ball, a box, a tin and a dice. Put each one at the top of a slope made with a book. Which ones roll? Then try to stack two of each. Make a list: rolls or stacks.
Practice
1
What is the name of this shape?
cube
2
Does a ball roll or can it be stacked easily?
It rolls.
3
Which shape can be stacked well: a sphere or a cube?
a cube
4
What is the name of this shape? If you lay it on its side and push it, does it roll?
It is a cylinder. Yes, it rolls on its curved side.