Skeleton Shapes

Skeleton Shapes

Skeleton shapes are made with balls of modelling clay and straws.

This shows a cube and a skeleton cube:

How many balls of modelling clay and how many straws does it take to make the cube?

Here are some piles of modelling clay balls and straws:

Look at the shapes below and decide which piles are needed to make a skeleton of each shape.

How do you know which piles go with which shape?

Why do this problem?

This problem helps children begin to become familiar with the various properties of common geometric solid shapes, concentrating on edges and vertices. It also helps in promoting discussion and experimentation. Naming the shapes should be a help during discussion and description of what has been done, rather than being an exercise in its own right.

Possible approach

Before doing this problem children should have had plenty of free play building with sets of solid shapes so that they begin to get a feel for their properties. They should also have chance to experiment with building skeleton shapes either with a specific kit or with drinking straws and modelling clay/plasticine.

Key questions

How many edges did you count? What does this tell you about the number of straws we need?
How many corners did you count? What does this tell you about the number of balls of modelling clay we need?
How many edges meet at this corner?

Possible extension

Possible support

Start by counting the faces on a cube - a large dice might be useful - and then the edges and finally the vertices. A non-permanent pen could be used to mark a real shape if children are having difficulty keeping track of their counting.