Table of Contents

Phase 2 - In Orbit

Estimating Angles

Teacher Notes

1. Estimating Angles provides a kinesthetic and visual way to reinforce the abstract concept that angles are parts of a circle and that as the rays change, so too does the angle measurement at the vertex. Estimating Angles is recommended as an extension activity to extend the discussion of angles.

2. This cooperative large group task can also generate discussion about the degree range differences between acute, right and obtuse angles.

3. This activity can be done as a whole class or students can be split up into 2 or more groups.

4. The completion time depends on the amount of discussion. It is suggested that 15-30 minutes be spent on the activity and recording.

5. Discussion points could include:

   • a. After a quarter turn is made, ask students to estimate the angle (90°).
   • b. After the next quarter turn (again 90°), discuss the formation of a straight line and a 180° angle.
   • c. After the next quarter turn (again 90°), ask students to calculate the reflex angle (270°).
   • d. Upon completion of the final quarter, discuss the circle concept of 360°.

Estimating Angles

Materials:

• Several metres of yarn or string

Hypothesis:

• As the rays of an angle are moved, the measure of the angle will change.

Procedure:

1. With your classmates, form a circle.

2. Have one person inside the circle hold the yarn or string at its centre point (the vertex).

3. Take turns having 2 other people on the circle hold the ends of the yarn or string (the rays).

4. Following the teacher’s directions, pass the ends of the string around the circle.

5. For each angle change, have a classmate record the group’s observations on chart paper.

Observations:

What happens to the angle when the outside people pass the ends of the string to someone else?

What type of angle is made with each change?

Estimate the measure of each different angle as the ends of the string are passed around the circle.

Conclusions:

What have you learned about angles from this experiment?

Did you prove or disprove the hypothesis that as the rays of an angle are moved, the angle measurement will change?

How could you determine the accuracy of your estimations?