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Worksheet

Extension & Challenge — 3D Space & Structures

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Part A — Counting Cubes & Volume

Volume is the amount of space a solid fills, measured in cubic units. For a rectangular prism, count the unit cubes — or multiply length × width × height. Do not forget the cubes hidden at the back and underneath.

Three isometric prisms made of unit cubes labelled A, B and C.
Three prisms built from unit cubes.
A rectangular prism with labelled length, width and height showing the volume formula.
Volume of a rectangular prism = length × width × height.
1 Count the unit cubes that build each prism above (remember the hidden cubes at the back).

A:   B:   C: cubes

2 Prism A measures 3 long, 2 wide and 2 high. Show that length × width × height gives the same count you found in question 1.
3 Find the volume of a box that is 5 cm long, 3 cm wide and 2 cm high.

Volume = cm³

4 A cube has a side length of 4 cm. What is its volume?

Answer:

5 A prism is built from exactly 24 unit cubes. Give two different sets of whole-number dimensions it could have.
6 Reasoning. Prisms A and B above are different shapes but both use 12 cubes. Does the volume of a solid depend on its shape, or only on how many cubes fill it? Explain.

Part B — Nets & Solids

A net is a flat pattern that folds up into a solid. Studying nets helps you count a solid’s faces (flat surfaces), edges (where two faces meet) and vertices (corners).

Two nets: A is a cross of six squares; B is a square with four triangles attached.
Net A and Net B. Picture each one folding up.
1 Which solid does each net above fold into?

Net A:    Net B:

2 Complete the table for a cube.
SolidFacesEdgesVertices
Cube
Square pyramid
3 How many squares are in the net of a cube? How many of each shape are in the net of a square pyramid?
4 A solid has 2 triangular faces and 3 rectangular faces. Name the solid.

Answer:

5 Reasoning. Sketch one net that folds into a cube and one arrangement of 6 squares that does not. How can you tell the difference?
6 Prove it. For any of these solids, add the faces and vertices then subtract the edges (F + V − E). Do it for the cube and the square pyramid. What do you notice?