Nets of 3D Objects
Connect objects to their nets and build objects from their nets using spatial and geometric reasoning.
Read this first
A net is a solid opened out flat. Fold it up and you get the shape back.
Six squares fold up to make a cube.
Words you need
- Net
- A flat shape that folds into a solid.
- Face
- One flat side of a solid.
- Edge
- Where two faces meet.
Worked example
e.g. How many squares are in the net of a cube?
- Think about a cube. Count its flat faces.
- Top, bottom, front, back, and two sides. That is six.
- So the net needs six squares.
- A cube net has 6 squares.
Count the faces of the solid. That is how many shapes the net needs.
Practice
The pictures fade as you go. By the last few you are on your own.
1How many faces has a cube?with a picture
AnswerSix.
2A net has 6 rectangles. What solid does it make?with a picture
AnswerA rectangular prism.
3What shapes are in the net of a triangular prism?with a hint
Need a hint?
Look at the ends and the sides.
Answer2 triangles and 3 rectangles.
4What shapes make the net of a cylinder?with a hint
Need a hint?
Think about the top, bottom and curved side.
Answer2 circles and 1 rectangle.
5How many edges has a cube?on your own
AnswerTwelve.
6Can a cube net be laid out in more than one way?on your own
AnswerYes. There are eleven different ones.
7How would you test if a net works?on your own
AnswerCut it out and fold it up.
Think about it
1
Why is a net useful?
One good answerIt shows every face at once, which a drawing cannot.
2
What must be true for a net to fold up?
One good answerNo two faces may overlap when folded.
Common mistakes
Thinking any six squares make a cube.
They must be joined in the right places.
Forgetting the hidden faces.
Count all six, including the back and bottom.