New
New
Year 4
Calculate the side length of a regular polygon by division where the perimeter is known
I can use division to calculate the side length of a regular polygon when the perimeter is known.
New
New
Year 4
Calculate the side length of a regular polygon by division where the perimeter is known
I can use division to calculate the side length of a regular polygon when the perimeter is known.
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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.
Keywords
Perimeter - The distance around a two-dimensional shape.
Regular - A regular polygon has all sides equal and all angles equal.
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.
Known multiplication facts are key in this lesson and pupils should be increasingly fluent in tables learned in Years 2 and 3. Multiplication grids may be a useful scaffold for less confident pupils.
Teacher tip
Licence
This content is © Oak National Academy Limited (2024), licensed on
Open Government Licence version 3.0
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
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Starter quiz
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6 Questions
Q1.
Select all of the squares.
c
d
Q2.
What is the perimeter of a square with a side length of 5 cm? cm.
Q3.
What is the perimeter of a regular triangle with a side length of 5 cm? cm.
Q4.
What is the perimeter of a regular pentagon with a side length of 5 cm? cm.
Q5.
Lucas is trying to work out 20 ÷ 5 but he is struggling. How else might he think of this question?
5 + _ = 20
20 − 5 = _
Q6.
Order these shapes from smallest perimeter to longest.
Exit quiz
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6 Questions
Q1.
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.
Nothing. It is not possible.
Q2.
What is the side length of a square with a perimeter of 16 cm?
2 cm
8 cm
64 cm
Q3.
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.
Q4.
What is the side length of a regular triangle with a perimeter of 15 cm? cm.
Q5.
What is the side length of a regular five-sided shape with a perimeter of 30 cm? cm
Q6.
What is the side length of a regular five-sided shape with a perimeter of 300 cm? cm.