4
Sorting and naming
Learner’s Book 1: Unit 10, pp. 152–154
GoalSort shapes into curved and straight, and name the faces and edges of 3D shapes.
New words
curved · bending, not straightstraight · not bendingedge · the line where two faces meet
Explanation
We can sort shapes in different ways. One way is by curved or straight. A circle has a curved side. A square, a rectangle and a triangle have straight sides. A sphere has a curved surface. A cube, a cuboid and a pyramid have straight edges. Look at a 3D shape. A flat side is a face. The line where two faces meet is an edge. A face of a cube is a square, a face of a cuboid is a rectangle, and a side face of a pyramid is a triangle.
| curved | straight sides or edges |
|---|---|
| circle, sphere, cylinder | square, rectangle, triangle, cube, cuboid, pyramid |
Worked examples
On a cube, a flat square side is a face. The line where two faces meet is an edge.
| curved | straight |
|---|---|
| sphere, circle | cube, triangle |
A pyramid with a square base has a square face at the bottom and 4 triangle faces.
Class activity
Sorting hoops: make two rings from string and label them ‘curved’ and ‘straight’. Put objects in the right ring (a ball, a tin, a book, a box, a paper triangle, a plate). Count each ring. Which has more? Is there one that could go in both?
Practice
1
Does a triangle have curved sides or straight sides?
Straight sides.
2
What is the shape of the faces on this cuboid?
rectangles
3
Which of these have a curved surface or side: circle, square, sphere, cube?
The circle and the sphere.
4
Is the flat side of this pyramid a face or an edge?
A face. The line where two faces meet is an edge.