Complementary angles

Complementary angles are two angles with a sum of 90°. A common case is when they form a right angle.

Objectives
Introduce children to concept of complementary angles

Estimated Time
30 minutes

Prerequisites/Instructions, prior preparations, if any
Prior knowledge of point, lines, angles

Materials/ Resources needed

 * Digital : Computer, geogebra application, projector.
 * Non digital : Worksheet and pencil.
 * Geogebra files : Complementary angles.ggb

Process (How to do the activity)

 * Prior hands on activity (optional – children can use news paper strips to make angles and place them together and notice if the resulting angle formed is a right angle).
 * Students should be able to identify the types of angles in the file
 * Let them attempt to join the two angles -They may try by coinciding different points or lines.
 * Ask about the angle formed by joining the two angles?
 * Challenge them to find another way to make a right angle using the two existing angles.
 * Interchanging the position of the two angles – ask what they notice.
 * If one angle is changed will the two together again form a complementary angle.
 * Children can be asked to make note of the angle measures for different angles work sheet
 * Observations made with angles seen so far.
 * Ask if the angles have to be adjacent to be complementary pairs
 * Record the values of the two angles and their sum in the worksheet
 * {| class="wikitable"


 * Sl No.
 * Value of slider α
 * Angle ABC
 * Angle DEF
 * Sum

Angle ABC + Angle DEF
 * Is angle ABC complement of angle DEF
 * }
 * Evaluation at the end of the	activity
 * 1) What are complementary pair of	angles?
 * 2) Is it required for the pair of	angles to be adjacent to be complementary?
 * 3) What types of angles form	complementary pair?
 * }
 * Evaluation at the end of the	activity
 * 1) What are complementary pair of	angles?
 * 2) Is it required for the pair of	angles to be adjacent to be complementary?
 * 3) What types of angles form	complementary pair?
 * 1) Is it required for the pair of	angles to be adjacent to be complementary?
 * 2) What types of angles form	complementary pair?