Make, explore and discuss regular and irregular 2 D shapes using a variety of materials.

Learning Intentions

To understand that a regular shape is a 2D shape where all (interior) angles and sides measure the same. 
To know that an irregular shape is a shape which has sides and angles of any length and size.

To learn the names of various shapes.

Introduction

Look at the regular shapes below. The word ‘equal’ tells us that the sides are the same length and the interior angles are the same size.

What are irregular shapes?

Irregular means not even or balanced. Irregular shapes (or polygons) are often much harder to name because they don’t look like the regular shapes. In fact, they can be any straight-sided shape. Their name is often determined by the number of straight sides that they have, although some irregular polygons have special names like parallelograms, rhombus or kite. Here are some examples:

Main learning

Some shape names are much easier to remember than others, most know what a circle and a square are, for example. Triangles are also fairly straightforward; however, the only regular triangle is equilateral. The clue here is in the name (equal).

A Pentagon takes its name from the Greek language; pente, meaning five and gonia, meaning angle.

Hexagons can be remembered in two ways. Just like the number six, they have an ‘x’ in their name and they have six sides.

Heptagons are a little trickier, again the name is Greek in origin, but we come across them less often so it can be a struggle to remember. A 50p coin is a Heptagon.

An Octagon has eight sides just like an octopus.

Classify the shapes on your table using the following Carrol diagram.