Things around us have all sorts of shapes. Some are flat – like a sheet of paper or a tile. Others have height as well – you can pick them up and turn them around. Flat shapes are called plane figures, three-dimensional shapes are called solids.
In this chapter you will learn to:
recognise the seven basic solids
name each solid
count its faces, edges, and vertices
find a solid in everyday objects
Plane figure vs solid
A square, a circle, or a triangle can be drawn on a sheet of paper. They are plane figures. They have only length and width, no thickness.
A cube, a ball, or a can also have height or thickness. You can hold them in your hand. They are solids.
The seven basic solids
In this chapter you meet seven solids:
Cube – like a die, six equal square faces
Cuboid – like a shoebox, flat faces of different sizes
Sphere – like a ball, perfectly round on every side
Cylinder – like a can or a pencil, circles on top and bottom
Cone – like an ice-cream cone, pointy on top
Pyramid – like an Egyptian pyramid, pointy on top with a square base
Prism – like a tent or roof, two triangles and three rectangles
Faces, edges, and vertices
Solids with flat faces (cube, cuboid, pyramid, prism) have three important parts you can count:
Face – a flat surface (like a page in a book)
Edge – a line where two faces meet
Vertex – a pointy corner where at least three edges meet
Solid
Faces
Edges
Vertices
Cube
6
12
8
Cuboid
6
12
8
Square pyramid
5
8
5
Triangular prism
5
9
6
For the sphere, cylinder, and cone we usually do not count faces, edges, and vertices the same way – they have curved surfaces.
