E2.3 Use the properties of supplementary angles, complementary angles, opposite angles, and interior and exterior angles to solve for unknown angle measures.
Activity: Complementary and Supplementary Angles
Task 1: Guided Instruction
Material
- Elastics aproximately three metres in length
Instructions
Place students in teams of three.
Give each team an elastic.
Ask them to take turns creating a given angle and naming it.
Facilitate discussions as needed.
Task 2: Guided Instruction
Material
- Pipe cleaners or Geostix and brass paper fasteners
Instructions
Demonstrate complementary angles.
- With two Geostix and a brass paper fastener, construct a right angle.
- Place a pipe cleaner in the right angle so that one end of the pipe cleaner is at the vertex of the right angle.
Ask the following questions:
- What is the approximate measure of each of the angles created?
- What is the sum of the two angles created? How do you know? (Two angles whose sum is 90° are called complementary angles even when they are not adjacent.)
Demonstrate supplementary angles.
- Attach two Geostix or pipe cleaners to create a straight angle.
- Attach a 3rd Geostix to the top of the straight angle and position it somewhere between its two sides.
Ask the following questions:
- What is the approximate measure of each of the angles created?
- What is the sum of the two angles created? How do you know? (Two angles whose sum is 180° are called supplementary angles, even when they are not adjacent.)
Task 3: Group Learning
Material
- Elastics about three metres long
Instructions
Have students form teams of six and give each team two elastics.
Have them construct complementary and supplementary angles.
Challenge students to create angles that are not adjacent.
Each team takes turns showing their complementary and supplementary angles to the rest of the class.
Task 4: Individual Learning
Material
- Geoboards and elastics
Instructions
On a Geoboard, students construct adjacent or non-adjacent complementary and supplementary angles.
Students show their angles to the rest of the class and explain what they did.
Task 5: Individual Learning
Material
- Math Journal
In their math journals, students explain, in their own words, complementary and supplementary angles, and draw examples of them.
Source: translated from L'@telier - Ressources pédagogiques en ligne (atelier.on.ca).