What are the properties of 2D and 3D shapes?
2D shapes: sides and vertices
When we talk about 2D shapes, we talk about sides and angles.
The angles of a 2D shape are also sometimes referred to as 'vertices' (singular: vertex).
For example: this 2D shape has four sides and four angles:
3D shapes: faces, edges and vertices
When we talk about 3D shapes, we talk about faces, edges and vertices.
The faces are the flat parts of the shape.
The edges are the lines where two faces meet.
The vertices are the points where two or more edges meet.
For example, this 3D shape has 6 faces, 12 edges and 8 vertices:
When do children learn about shapes' properties?
Children in Key Stage 1 will discuss 2D and 3D shapes using the above terms (although they may say 'corners' instead of angles or vertices). They will talk about how many sides a 2D shape has, and whether the sides are straight or curved.
It is very important that they handle 3D shapes in order to be able to count their faces, edges and vertices, so they will probably construct their own 3D shapes from nets.
They will also need to be able to look for lines of symmetry in a 2D shape. They may check this by folding a shape in half to see if the two halves match up.
Children will continue to use the above terms to describe 2D and 3D shapes in Key Stage 2. They will also start using the following terms:
Children need to be able to recognise right angles (90˚). They may be encouraged to use the corner of a book to test whether something is a right angle or not.
An acute angle is an angle that measures less than 90˚.
An obtuse angle is an angle between 90˚ and 180˚.
When two lines are parallel, they are always an equal distance from each other.
When two lines are perpendicular, they are at right angles to each other.