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2D shapes are everywhere!

For example, windows are usually shaped like rectangles and clocks are shaped like circles.

2D shapes are flat and all have different properties.

A property is a quality that a shape has. Examples of shape properties are:

• number of sides
• number of vertices (corners)
• length of sides
• types of angles (acute, obtuse, right-angle)
• perpendicular and parallel lines

Here are three 2D shapes. What properties do they have?

All triangles have 3 sides and 3 angles.

Their internal angles add up to 180°.

However, different triangles have different properties, depending on how they are drawn.

The types of triangle are:

• isosceles
• equilateral
• scalene
• right-angled

A quadrilateral is a shape with 4 sides and 4 angles.

These are some examples of quadrilaterals and their properties:

Rectangle

• 2 pairs of equal sides.

• Angles all right-angles (perpendicular lines).

• 2 pairs of parallel lines.

Square

• A special type of rectangle.

• Sides all equal length.

• Angles all right-angles (perpendicular lines).

• 2 pairs of parallel lines.

Trapezium

• 1 pair of parallel lines.

• 2 sets of equal angles.

• 2 lines equal length and 2 that aren’t.

Kite

• 2 pairs of equal sides.

• 1 pair of equal angles.

• No parallel lines.

These are shapes that have all equal sides and equal angles.

Pentagon

• 5 equal sides and angles.

Hexagon

• 6 equal sides and angles.

• 3 pairs of parallel lines.

Heptagon

• 7 equal sides and angles.

Octagon

• 8 equal sides and angles.

• 4 pairs of parallel lines.

These are shapes that have sides and angles of different sizes.

You can always identify the polygon by how many sides it has, eg. a pentagon is always a shape that has 5 sides.

Example:

This irregular pentagon has sides and angles that are different lengths and sizes.

It has two right angles and one pair of equal sides. The other 3 sides are different lengths.

2D shape hunt

Let's see what 2D shapes we can find around the house.

You will need a pencil and a piece of paper.

Look around the house for 2D shapes. Draw them on your piece of paper.
Can you draw and label:

• the sides
• the vertices