The three objects on the board are:

• a honeycomb cell, with 6 straight edges
• an octagonal stop sign, with 8 straight edges
• a six-sided metal nut, with 6 straight edges

Do all the edges on one object look the same length, or are some longer than others?

A polygon is a closed flat shape made only of straight sides. Look at the two hexagons on the board. Look at the sides of each one. If every side matches and every corner matches, the shape is regular. If some sides are different lengths, it is irregular.

Regular means all the sides are equal and all the corners are equal. The last shape is a hexagon that looks a bit odd. Be ready to say what makes it different from the honeycomb hexagon.

A pentagon has 5 sides, a hexagon has 6 and an octagon has 8. Regular means those sides are all equal.

Today we sort these polygons together: a pentagon, another pentagon, a hexagon, another hexagon, an octagon, and an octagon that has one short side.

For each shape, we check every side before we decide.

We'll work through four sorts, each a bit harder:

• clear regular shapes against clearly irregular ones
• a regular shape turned on its side, so it looks unfamiliar
• shapes that look regular but have one short side
• a full mix of pentagons, hexagons and octagons to name and sort