P5 Maths — Nets of Solids (Answer Key)
Every answer with the folding reason
Created by Miss Clarissa Ng · www.clartutors.com
Answer key — is it a net of a cube?
Answers with the reason. Every one of these was checked by folding the cube square by square, not by eye.
Net A — YES
Number the squares 1, 2, 3, 4 along the straight line: 1 and 3 fold opposite each other and 2 and 4 fold opposite each other. The two squares that stick out of the line take the last two faces. Six different faces, nothing left over — it is a net.
Net B — NO
It contains a 2 × 2 block of squares — four squares that would fold onto only three faces, so a face of the cube is left empty.
Net C — NO
It has five squares in a straight line. Fold a strip of five and the first and the fifth square land on the same face.
Net D — YES
Number the squares 1, 2, 3, 4 along the straight line: 1 and 3 fold opposite each other and 2 and 4 fold opposite each other. The two squares that stick out of the line take the last two faces. Six different faces, nothing left over — it is a net.
Net E — YES
The two groups fold around the cube in opposite directions, so the six squares take the six faces in turn — it is a net.
Net F — NO
It contains a 2 × 2 block of squares — four squares that would fold onto only three faces, so a face of the cube is left empty.
Net G — NO
It folds onto only 5 faces: 2 of its squares would land on the same face, so the cube would be left with a gap.
Net H — YES
Step around the cube square by square: each pair of squares carries you onto a new face. Six different faces, nothing repeated — it is a net.
Answer key — name the solid
A.
A cuboid — six rectangles in three matching pairs, so 6 faces.
B.
A square pyramid — one square and four triangles, so 5 faces.
C.
A triangular prism — two triangles and three rectangles, so 5 faces.
D.
A tetrahedron — four triangles, so 4 faces.