In this video the teacher uses the Motion of a Fly GSP to discuss what happens when there is a negative change in amount.
Worksheet 4, Clip 1, Discussion of Bug on Fan, 3:13
The teacher begins by asking how the motion of the fly corresponds to angle measure. This will help ensure the students understand what is going on in this task. It also creates an opportunity to revisit the class' agreed upon meaning of angle measure.
As a class they describe the bug's motion as creating a circle and thus tracking the distance it travels will correspond to angle measure. It is important that the students have this understanding of the situation before they proceed through the activity.
The teacher then uses the Motion of Fly Applet with a given radius (in this case 3.1 feet) to demonstrate the situation to the students. This is useful to help the students visualize the situation.
The teacher also takes the opportunity to reinforce what it means to have a measurement of 1 radian but tracing out 3.1 feet along the arc.
As a class they look at what it means to move 0.756 radians. Again, this is an opportunity to reinforce the meaning of radians.
Note how the teacher reinforces that they are working with a percentage of a radius. This type of reinforcement is necessary, particularly in the beginning of this module.
