Angles: Identification and properties of angles





Class : JSS1






Reference Materials

  • Scheme of Work
  • Online Information
  • Textbooks
  • Workbooks
  • 9 Year Basic Education Curriculum

Previous Knowledge :

The pupils have previous knowledge of


Angles: Identification and properties of angles (



Behavioural Objectives :  At the end of the lesson, the pupils should be able to

  • define angles 
  • explain properties of angles
  • write out types of angles
  • explain vertically opposite angles
  • say the meaning of corresponding angles






Angles: Identification and properties of angles (a) vertically opposite angles 

(b) adjacent angles (c) alternate angles (d) corresponding angles


What is an angle ?

An angle is formed when an arm moves from an initial position to a final position .

An angle is a point of interception between two or more lines .

Angles are measured in degrees.

A pair of compass , ruler and a pencil is needed to construct an angle . A protractor is used to measure angles



Properties of Angles 

  • The total sum of angles on a straight line is equal to 180 degrees
  • The value of an angle on a point is equal to 360 degrees
  • The sum of a right angle is equal to 90 degrees
  • Vertically opposite angles are always equal
  • Corresponding angles are equal.
  • Vertical angles are equal.
  • The sum of complementary angles is 90˚.
  • The sum of angles on a straight line is 180˚.
  • The sum of angles in a triangle is 180˚.
  • Alternate exterior and interior angles are equal


Types of Angles 

  • Acute Angles : These are angles whose values are lesser or smaller than 90 degrees eg angles that measured up to 40 degrees . 45 degrees . 89 degrees etc
  • Right Angles : These are angles whose values is 90 degrees .
  • Obtuse Angles : These are angles whose values are greater than ninety degrees but less than one hundred and eighty degrees
  • Angle on a straight line : The values of angles on a straight is equal to one hundred and eight degrees .
  • Reflex Angles : Angles that are greater than 180 degrees but less than 360 degrees
  • Angle at a point : The value of this angle is equal to 360 degrees .





The topic is presented step by step


Step 1:

The class teacher revises the previous topics


Step 2.

He introduces the new topic


Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise









  1. What is an angle ?
  2. How is an angle formed ?
  3. What tools are used to construct angles
  4. What is a protractor
  5. What is an acute angle
  6. what is an obtuse angle
  7. define a reflexive angle
  8. Draw an acute angle
  9. Draw an angle on a straight line
  10. What is an angle at a point called ?






Conclusion :


The class teacher wraps up or conclude the lesson by giving out short note to summarize the topic that he or she has just taught.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she does the necessary corrections when and where  the needs arise.







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