Flat shapes are 2D. We count their sides and corners. A pentagon has 5 sides and a hexagon has 6. Solid shapes are 3D. They have faces (flat surfaces), edges (where faces meet) and vertices (corners).
A cube has 6 square faces, 12 edges and 8 vertices. A cylinder has 2 flat circle faces and one curved surface. A sphere, like a ball, is curved all over.
Worked example
How many edges does a cube have?
- Count the 4 edges on the top and the 4 on the bottom.
- Add the 4 edges going up the sides: 4 + 4 + 4.
Answer:12 edges
Key words
- face
- a flat surface of a solid
- edge
- where two faces meet
- vertex
- a corner; more than one are vertices
Practise this
New questions every time.
Common Core-referenced: 2.G.A.1