Starter quiz
- Select all of the squares.
a ✓
b ✓
c
d
- What is the perimeter of a square with a side length of 5 cm? ______ cm.
- '20' ✓
- What is the perimeter of a regular triangle with a side length of 5 cm? ______ cm.
- '15' ✓
- What is the perimeter of a regular pentagon with a side length of 5 cm? ______ cm.
- '25' ✓
- Lucas is trying to work out 20 ÷ 5 but he is struggling. How else might he think of this question?
- 5 + _ = 20
- _ × 5 = 20 ✓
- 5 × _= 20 ✓
- 20 − 5 = _
-
- Order these shapes from smallest perimeter to longest.
- 1⇔A regular triangle with a side length of 5 cm
- 2⇔A square with a side length of 4 cm
- 3⇔A regular pentagon with a side length of 4 cm
Exit quiz
- If you know the perimeter of a regular polygon, what can you do to find the length of each side?
- Divide the number of sides by the perimeter.
- Divide the perimeter by the number of sides. ✓
- Nothing. It is not possible.
-
- What is the side length of a square with a perimeter of 16 cm?
- 2 cm
- 4 cm ✓
- 8 cm
- 64 cm
-
- Lucas has measured the perimeter of his classroom, which is square-shaped. Its perimeter is 24 metres. What is the length of one side of the classroom? ______ m.
- '6 ' ✓
- What is the side length of a regular triangle with a perimeter of 15 cm? ______ cm.
- '5' ✓
- What is the side length of a regular five-sided shape with a perimeter of 30 cm? ______ cm
- '6' ✓
- What is the side length of a regular five-sided shape with a perimeter of 300 cm? ______ cm.
- '60' ✓
Worksheet
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Presentation
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Lesson Details
Key learning points
- If you know the perimeter of a regular polygon you can calculate the length of one side.
- Divide the perimeter by the number of sides to calculate the length of one side.
- Knowledge of times tables and related division facts can support calculation.
Common misconception
Pupils often find division a trickier concept than multiplication and do not connect this to their known multiplication facts.
Establish the inverse relationship with multiplication and show how the division equations can be re-written as a multiplication equation with a missing factor. Support pupils in making this connection to allow them to use known facts to calculate.
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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