4
Fitting shapes together
Learner’s Book 1: Unit 2, pp. 46–47
GoalUse what you know about 2D and 3D shapes: find the shape with a number of sides, say which shapes fit together with no gaps, and say which 3D shapes go through a round hole.
New words
gap · an empty space between shapesfit · go into a space exactlyhole · an opening you can put things through
Explanation
Some shapes fit together with no gaps. Squares fit side by side. Rectangles fit well too, and so do triangles. Circles do not: they always leave gaps between them. A round hole is shaped like a circle. A small sphere can go through it, and so can a thin cylinder standing up, because their ends are round. A cube as wide as the hole cannot go through, because its corners stick out. Remember: a cube has 6 flat faces, a cylinder has 2 and a sphere has none.
| shape | fits with no gaps? |
|---|---|
| square | yes |
| rectangle | yes |
| triangle | yes |
| circle | no: gaps are left |
Worked examples
Which shape has 3 sides? Look at the sides: the rectangle has 4, the circle has 1, the triangle has 3.
A box has a round hole. The hole is a circle, like this.
Squares fit side by side with no gaps. Put circles side by side and gaps are left.
Class activity
Posting game: cut a round hole in a cardboard box, about as wide as a tin can. Try the tin standing up, a small ball and a big cube-shaped box. Which go through? Which do not? Then try covering a page with only squares, and again with only circles.
Practice
1
Which shape has 4 sides: the triangle, the rectangle or the circle?
the rectangle
2
Which shapes fit together with no gaps: squares or circles?
squares
3
Which 3D shape has 6 flat faces: sphere, cylinder or cube?
cube
4
A box has a round hole. Will a sphere go through? Will a big cube?
A small sphere can go through, because it is round. The big cube cannot: its corners stick out.