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Checking and securing understanding of basic angle facts

I can confidently calculate with angles at a point, angles on a line and vertically opposite angles.

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Lesson 2 of 10

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Year 10

Checking and securing understanding of basic angle facts

I can confidently calculate with angles at a point, angles on a line and vertically opposite angles.

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Lesson details

Key learning points

Angles that meet around a point sum to 360°
Angles that make a straight line sum to 180°
Vertically opposite angles are equal.

Keywords

Angle - An angle is a measure of turn. It is often displayed as the rotation between two line segments.
Sector - A sector is the region formed between two radii and their connecting arc.

Common misconception

Angles on a straight line sum to 180°

Angles that meet about a single point on a straight line sum to 180°. If the angles are not adjacent, then they may not necessarily sum to 180°.

There is a check for this misconception in the second learning cycle of this lesson. Depending on your pupils, you may wish to adapt this check to hide the justifications until after pupils have decided whether the statement is true or false or remove them and have pupils justify to each other.

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Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Prior knowledge starter quiz

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6 Questions

Q1.
A __________ is the region formed between two radii and their connecting arc.

circle

circumference

diameter

Correct answer: sector

Q2.
What is the size of the angle marked $$x$$?

67°

73°

Correct answer: 113°

127°

Q3.
What is the size of the angle marked $$x$$?

Correct answer: 67°

73°

113°

127°

Q4.
The size of the angle marked $$x$$ is °.

Correct Answer: 240, two hundred and forty

Q5.
Match each angle to its size.

Correct Answer:∠BCD,113°

Correct Answer:∠CDA,92°

Correct Answer:∠ABC,90°

Correct Answer:∠DAB,65°

Q6.
The three letter notation for the marked angle is ∠ .

Correct Answer: FMA, AMF

Assessment exit quiz

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6 Questions

Q1.
Angles around a point sum to °.

Correct Answer: 360, three hundred and sixty

Q2.
Angles that meet at a point on a straight line sum to °.

Correct Answer: 180

Q3.
Vertically opposite angles are __________.

conjugate

Correct answer: equal

supplementary

Q4.
The size of ∠BEA is 70°. Therefore the size of the obtuse angle ∠CEB is °.

Correct Answer: 110, one hundred and ten

Q5.
The size of ∠BEA is 70°. Therefore the size of the acute angle ∠DEC is °.

Correct Answer: 70, seventy

Q6.
The size of ∠BEA is 70°. Therefore the size of the reflex angle ∠AEB is °.

Correct Answer: 290, two hundred and ninety

Lesson appears in

UnitMaths / Angles

Maths

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Checking and securing understanding of basic angle facts

Checking and securing understanding of basic angle facts

Lesson slides

Lesson details

Key learning points

Keywords

Common misconception

Licence

Lesson video

Worksheet

Prior knowledge starter quiz

6 Questions

Q1.A __________ is the region formed between two radii and their connecting arc.

Q2.What is the size of the angle marked $$x$$?

Q3.What is the size of the angle marked $$x$$?

Q4.The size of the angle marked $$x$$ is °.

Q5.Match each angle to its size.

Q6.The three letter notation for the marked angle is ∠ .

Assessment exit quiz

6 Questions

Q1.Angles around a point sum to °.

Q2.Angles that meet at a point on a straight line sum to °.

Q3.Vertically opposite angles are __________.

Q4.The size of ∠BEA is 70°. Therefore the size of the obtuse angle ∠CEB is °.

Q5.The size of ∠BEA is 70°. Therefore the size of the acute angle ∠DEC is °.

Q6.The size of ∠BEA is 70°. Therefore the size of the reflex angle ∠AEB is °.

Lesson appears in

UnitMaths / Angles

Maths

Q1.
A __________ is the region formed between two radii and their connecting arc.

Q2.
What is the size of the angle marked $$x$$?

Q3.
What is the size of the angle marked $$x$$?

Q4.
The size of the angle marked $$x$$ is °.

Q5.
Match each angle to its size.

Q6.
The three letter notation for the marked angle is ∠ .

Q1.
Angles around a point sum to °.

Q2.
Angles that meet at a point on a straight line sum to °.

Q3.
Vertically opposite angles are __________.

Q4.
The size of ∠BEA is 70°. Therefore the size of the obtuse angle ∠CEB is °.

Q5.
The size of ∠BEA is 70°. Therefore the size of the acute angle ∠DEC is °.

Q6.
The size of ∠BEA is 70°. Therefore the size of the reflex angle ∠AEB is °.