Understand the idea.
Plan the pieces before cutting
Before drawing a net, list the solid faces and their dimensions. Each outside surface needs one panel. Faces that meet must have matching edge lengths, so check the whole list before cutting.
Use a ruler and distinguish fold lines between panels from cut lines around the outside. Joining tabs sit outside the face panels and fold inside for gluing. They do not become additional outside faces.
Use dimensions consistently
A rectangular box has three pairs of matching faces: top and bottom, front and back, left and right. Each pair uses two of the box dimensions. A cube is the special case where all six faces are equal squares.
Test the folding before decorating. Wrong edge lengths can leave gaps even with the correct face count. Keep tabs separate from face area, and ask an adult for cutting help when needed.
See the method in action.
Make a 2 cm cube
Describe the faces and face area needed for a cube of edge 2 cm.
Worked solution
- 1
Specify the six face panels.
A cube has six equal square faces, and each side is the cube edge length.
- 2
Find one face area.
Each square covers a 2-by-2 array of square centimetres.
- 3
Find the total face area.
Six separate equal faces are needed; joining tabs are excluded from this total.
Six 2 cm squares; total face area 24 square centimetres.
Plan a rectangular box
List the faces of a box 4 cm long, 3 cm wide and 2 cm high.
Worked solution
- 1
Plan the top and bottom.
These faces use the box length and width.
- 2
Plan the front and back.
These faces use the length and height.
- 3
Plan the left and right sides.
These faces use the width and height.
- 4
Check the complete face list.
The three matching pairs cover all sides; edges joined in a net must have equal lengths.
Two of each: 4×3, 4×2 and 3×2 cm.
Try it yourself.
Check your understanding
How many equal squares must you draw for a cube net?
Show answer & reasoning
Six.
A cube has six square outside faces, so its net needs six equal square panels. Tabs can be added for joining, but they do not change the face count.
Keep practising
6 worksheet questions · 14 marks
Read the questions online
- Draw a valid cube net with square edges 2 cm long. Label each face.3 marks
- Find the total face area of a cube whose edges are 3 cm.2 marks
- A box measures 5 cm by 3 cm by 2 cm. List all six face sizes.3 marks
- A triangular prism has equilateral triangular ends of side 3 cm and length 5 cm. What rectangular side panels are needed?2 marks
- Explain why a 4 cm edge should not be joined to a 3 cm edge without cutting or changing the model.2 marks
- Draw one joining tab on a cube-net sketch and explain whether it counts as a seventh face.2 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Draw a valid cube net with square edges 2 cm long. Label each face.3 marks
Use six equal squares; a row of four with one above and one below the second square is valid.
Check equal shared edges.
Any valid six-square cube net with 2 cm edges. - Find the total face area of a cube whose edges are 3 cm.2 marks
Each face has area .
Six faces have area .
54 square centimetres. - A box measures 5 cm by 3 cm by 2 cm. List all six face sizes.3 marks
Use one pair for each pair of dimensions.
Two cm; two cm; two cm. - A triangular prism has equilateral triangular ends of side 3 cm and length 5 cm. What rectangular side panels are needed?2 marks
Each of the triangle's three 3 cm sides extends along the prism's 5 cm length.
Three rectangles, each 3 cm by 5 cm. - Explain why a 4 cm edge should not be joined to a 3 cm edge without cutting or changing the model.2 marks
The 1 cm difference leaves an overhang or a gap.
Their endpoints will not match. - Draw one joining tab on a cube-net sketch and explain whether it counts as a seventh face.2 marks
The cube still has six outside square faces.
The tab is outside an edge and folds inside; it is not another face.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Connect objects and two-dimensional nets; construct and explain spatial relationships.
Official curriculum source ↗