A net is a solid cut open and laid flat. To name the solid, look at the faces. Six equal squares make a cube; six rectangles in matching pairs make a rectangular prism. Two matching end shapes joined by a strip of rectangles make a prism, named after the end shape: two triangles and three rectangles make a triangular prism. One base with triangles all round it makes a pyramid, named after its base. Two circles and a rectangle make a cylinder; one circle and a curved fan make a cone. Name the solid, not a flat face.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- net
- a flat shape that folds up to make a solid
- face
- a flat surface of a solid
Worked examples
A net has 6 equal squares. Which solid does it fold up to make?
- 1.All six faces are the same square.
- 2.Six equal squares fold into a cube.
= cube
A net has 1 square and 4 triangles around it. Which solid does it fold up to make?
- 1.The triangles fold up to meet at a point.
- 2.The base is a square.
= square pyramid
A net has 2 hexagons and 6 rectangles. Which solid does it fold up to make?
- 1.Two matching hexagon ends joined by rectangles.
- 2.A prism named after its hexagon ends.
= hexagonal prism
For parents
Method: Count the face shapes, find the base, then decide prism or pyramid.
What to say: Which faces match? Do the triangles meet at a point, or are there two ends the same?
Common mistakes:
- Names the base correctly but mixes up prism and pyramid (or cylinder and cone).
- Calls any box shape a cube without checking that all six faces are equal squares.
- Names a flat face in the net (square, triangle, circle) instead of the solid it folds into.
- Uses the total number of faces to name the base (a square pyramid has 5 faces, so calls it pentagonal).