Starter quiz
- Continue the sequence: 3, 6, 9, 12, ______
- '15' ✓
- Which of these numbers would you say if you were counting in fours from zero?
- 14
- 16 ✓
- 22
- 48 ✓
-
- Match the number of sides to the shape name.
- 3 equal sides⇔regular triangle ✓
- 4 equal sides⇔square ✓
- 5 equal sides⇔regular pentagon ✓
- 6 equal sides⇔regular hexagon ✓
- What is the side length of a square with a perimeter of 20 cm?
- 4 cm
- 5 cm ✓
- 10 cm
- 80 cm
-
- What is the side length of a regular triangle with a perimeter of 30 cm? ______ cm
- '10' ✓
- What is the side length of a regular five-sided polygon with a perimeter of 25 cm? ______ cm.
- '5' ✓
Exit quiz
- A regular triangle and a square have the same perimeter, which is a whole number. What could the perimeters be?
- 6
- 8
- 12 ✓
- 15
-
- A regular triangle and a square each have a perimeter of 12 cm. What is the side length of each shape?
- The triangle has a side length of 3 cm.
- The triangle has a side length of 4 cm. ✓
- The square has a side length of 3 cm. ✓
- The square has a side length of 4 cm.
-
Shape A is a square with a perimeter of 16 cm. A new shape has been composed from copies of shape A. What is its perimeter? ______ cm.- '32' ✓
Shape A is a square with a perimeter of 16 cm. A new shape has been composed from copies of shape A. What is its perimeter? ______ cm.- '32' ✓
Shape A is a square with a perimeter of 12 cm. A new shape has been composed from copies of shape A. What is its perimeter? ______ cm.- '30' ✓
Shape A is a regular hexagon with a perimeter of 30 cm. A new shape has been composed from copies of shape A. What is its perimeter? ______ cm.- '60' ✓
Worksheet
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Presentation
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Lesson Details
Key learning points
- Perimeter is the sum of the side lengths of a 2D shape.
- Mental and written methods can be used to calculate the perimeter of a 2D shape.
- Combinations of addition, subtraction, multiplication and division can be used to solve problems involving perimeter.
Common misconception
Pupils may think that if they know the perimeter of a shape, and a new shape has been made from duplicates of it, they can simply multiply the perimeter by how many shapes make up the new one.
The lesson highlights this misconception and tackles it but it is worth being aware of it as pupils work. Point out to them that some of the sides from the original shape are now inside the new shapes so do not count as part of its perimeter.
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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