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Year 4

Know that a regular polygon has sides that are the same length and angles that are the same size

I know that a regular polygon has sides that are the same length and angles that are the same size.

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New
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Year 4

Know that a regular polygon has sides that are the same length and angles that are the same size

I know that a regular polygon has sides that are the same length and angles that are the same size.

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Share activities with pupils

Lesson details

Key learning points

  1. In a regular polygon, the sides are all the same length and the angles are all the same size
  2. In an irregular polygon the sides and angles are not all the same sizes
  3. Irregular polygons can have some angles and sides the same sizes

Common misconception

Many polygons appear regular as all of the sides are the same length. However, it is possible (as the lesson shows) to have polygons which are the same length sides but different interior angles.

Pupils should have previous experience of right angles. Use a right angle 'measurer' to prove that some of the angles in a shape are greater than a right angle and some smaller; as the angles are not all equal, it is not a regular polygon.

Keywords

  • Regular polygon - A polygon where all angles are equal and all side lengths are equal.

  • Irregular polygon - A polygon where not all angles are equal and / or not all side lengths are equal.

  • Interior angles - Interior angles are the angles formed inside a polygon by two of its sides.

If you have access to two-dimensional shapes, it is recommended that you design the lesson to incorporate opportunities to explore the concepts covered using these. Pupils can sort them into polygons / not polygons then take the polygons and re-sort them into regular polygons / not regular polygons.
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).

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Starter quiz

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6 Questions

Q1.
Match the shape to the correct name.
An image in a quiz
Correct Answer:a,hexagon

hexagon

Correct Answer:b,square

square

Correct Answer:c,pentagon

pentagon

Q2.
Which of these shapes has right angles?
equiliateral triangle
Correct answer: square
regular pentagon
Q3.
Which of these shapes are squares?
A
Correct answer: B
Correct answer: C
D
Q4.
Which of these are straight lines?
Correct answer: A
Correct answer: B
C
Q5.
Select all the shapes that have only straight sides.
A
Correct answer: B
C
Correct answer: D
Q6.
Select all the two-dimensional (2D) shapes.
A
Correct answer: B
C
Correct answer: D

Exit quiz

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6 Questions

Q1.
Select all of the statements that are true of polygons.
They are three-dimensional shapes.
Correct answer: They have all straight sides.
Correct answer: They have all closed sides.
All interior angles are right angles.
Q2.
Which of these shapes is a regular polygon?
Correct answer: A
B
C
D
Q3.
Which of these shapes are regular polygons?
A
B
Correct answer: C
Correct answer: D
Q4.
This shape has been made by putting number rods together. Select all of the statements that are true.
An image in a quiz
Correct answer: The sides are equal in length.
The sides are different lengths.
The interior angles are equal.
Correct answer: The interior angles are unequal.
It is a regular polygon.
Q5.
These shapes have been made by putting number rods together. Look closely at the sides shown by the lines. Which one is a regular polygon?
A
B
Correct answer: C
Q6.
Select all of the statements that are true of regular polygons.
Correct answer: They are two-dimensional, closed shapes.
They are two-dimensional, open shapes.
Correct answer: They have all straight sides.
No sides are equal in length
Correct answer: All interior angles are equal.