Starter quiz
- Which of these describe this shape?
- irregular polygon ✓
- regular polygon
- not a polygon
-
- What is the perimeter of this rectangle?
- 12 units
- 17 units
- 24 units ✓
-
- Select all of the regular polygons.
- a ✓
- b
- c ✓
- d
- Select all of the squares.
- a
- b ✓
- c ✓
- d
- Which of these red lines shows the perimeter of the triangle?
- a
- b ✓
- c
- d
- Match the shape to the correct number of sides.
- triangle⇔3 ✓
- square⇔4 ✓
- pentagon⇔5 ✓
- hexagon⇔6 ✓
- octagon⇔8 ✓
Exit quiz
- What is the perimeter of a square with a side length of 4 cm? ______ cm.
- '16' ✓
- What is the perimeter of a regular triangle with a side length of 4 cm? ______ cm.
- '12' ✓
- What is the perimeter of a regular pentagon with a side length of 4 cm? ______ cm.
- '20' ✓
- What is the perimeter of a regular octagon with a side length of 4 cm? ______ cm.
- '32' ✓
- Order these shapes from smallest perimeter to longest.
- 1⇔A square with a side length of 3 cm
- 2⇔A regular triangle with a side length of 5 cm
- 3⇔A regular pentagon with a side length of 4 cm
- Which of these shapes will have the same perimeter as each other?
- A regular triangle with a side length of 6 cm ✓
- A square with a side length of 4 cm
- A regular pentagon with a side length of 3 cm
- A regular hexagon with a side length of 3 cm ✓
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Worksheet
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Presentation
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Lesson Details
Key learning points
- If you know the length of one side of a regular polygon you can calculate the perimeter.
- Multiply the side length by the number of sides of the regular polygon to calculate the perimeter.
Common misconception
Pupils may overgeneralise and assume all perimeters can be calculated by multiplying one side length by the number of sides in the polygon.
'Noticing' is a key mathematical skill. Encourage pupils to take their time to notice whether the shape is regular or irregular, if that information is not already explicitly given.
Keywords
Perimeter - The distance around a two-dimensional shape.
Regular - A regular polygon has all sides equal and all angles equal.
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