2D and 3D Shapes — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A 2D shape is flat and has no thickness.
2D means two dimensions — only length and width — so the shape lies flat on paper with no depth you could measure.
2. A 3D shape takes up space and is solid.
A 3D shape has length, width, and height, which gives it real space to fill — that is what makes it solid like a block or ball.
3. A cube has 6 faces that are all the same size.
Every cube has 6 identical square faces — think of a number cube where each of the 6 sides is exactly the same size.
4. A triangular prism has 5 faces in all.
A triangular prism has 2 triangle faces on the ends and 3 rectangle faces wrapping around the sides, which adds up to 5 faces total.
5. A circle has 0 sides and 0 vertices.
A circle is one smooth curved line with no straight edges and no corner points, so both its number of sides and vertices are 0.
6. The flat surface of a 3D shape is called a face.
In geometry, the flat sides you can touch on a solid shape — like one square side of a cube — are each called a face.
7. A cylinder has 2 edges.
A cylinder has 2 edges — the circles formed where each flat circular face meets the curved side of the tube.
8. Where two faces of a 3D shape meet is called an edge.
When two flat faces come together on a solid shape, they form a straight line — and that line is called an edge.
9. A corner point on a 3D shape is called a vertex.
A vertex is the pointed corner where three or more edges meet on a solid shape, like the sharp corner of a cube.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each 3D shape to its number of faces.
cube
→ 6
5
triangular prism
→ 5
6
cone
→ 1
1
rectangular prism
→ 6
6
A cube and rectangular prism each have 6 flat faces (top, bottom, and 4 sides), a triangular prism has 2 triangles plus 3 rectangles for 5 total, and a cone has just 1 flat circular face at the bottom.