Page 84 - IM_FL_Geometry_Print Sample

b. How do you know is the center of the circle?
Student Response
1. Not every point on the shape is the same distance from some center point.
2. The point cannot be the center because the distance from points on the circle to the given point vary.
a.
3. b. The compass only draws points that are a xed distance from .
Activity Synthesis
The purpose of discussion is to clarify the de nition of a circle as the set of points equidistant to a given center point. Select students to share their responses. Push students to justify unsubstantiated claims and to use precise language. For example, if a student describes a circle as round, produce an example of a shape that is also round but not a circle.
1.3 What Do You Know about the Whole Circle?
20 minutes
The purpose of this activity is for students to use the tools they have available to analyze the relationship between a sector and the whole circle of which it is a part (MP5). The sector is chosen to have a central angle of 1 radian to anticipate work students will do in the next several lessons to de ne radian measure, calculate arc length, and calculate sector area. The image is marked with 1 rad, which may lead students to guess that there are just over 6 rad in the whole circle even though they do not yet know what a rad is.
Look for students who investigate the connections between angle measure, arc length, sector area, and chord length. These ideas will be explored further in subsequent lessons.
It is not necessary at this time for students to be introduced to the word chord.
Unit 7 Lesson 1: What’s a Circle? 11