Look at the paper plate. When it is whole, what shape is it? When it is folded in half, what new shape appears?
Where have you seen that half-moon shape before: a rainbow, an orange slice, the moon?
Look at this pizza. It is a circle: round all the way, with no straight sides and no corners.
Here the same pizza is in two equal pieces. The two pieces match. Each fair half is a semicircle (a fair half of a circle).
Look at one half on its own. A semicircle has one curved side and one straight side.
Today we sort pictures into two groups: circle or semicircle.
Look at each picture's shape. A coin is a small round disc. A button is round with holes. A rainbow has a curved top and a flat bottom. A melon slice is a curved wedge with a straight cut.
Ask: is it perfectly round all the way, or does it have one curved side and one straight side?
Circle or semicircle?
In your maths copy, draw a circle, then a semicircle beside it.
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