1. Quadrilateral Review Measure the length and width of your desktop.
Measure and calculate the distance around the outside of your desktop.
What unit did you use to measure your desks? Why?
What do we call the distance around the outside of an object?

2. Group Investigation Get into groups of 4
Member 1: Task leader-makes sure all students are participating and lets me know if the group needs help or has questions
Member 2: Recorder-keeps group copy of measurements and calculations from activity
Member 3: Measurer-measures items (other members should also check these measurements)
Member 4: Presenter-presents the group’s findings and ideas to the class
Pick your roles now…

3. Minds On: Measure the distance around different circular objects.
Distance Around (cm)
Radius
(cm)
Diameter
Stool
BUCKET
54.5cm
9.5cm
19cm
White board maker
5.7cm
0.7cm
1.4cm
Paint
22cm
3cm
7cm
Elephant skin ball
55cm
27.5cm
Broom handle
7.5cm
1.5cm
6.1 Radius and Diameter of a Circle

4. Consolidation: What patterns do you see? What do you notice?
Perimeter
-The distance around a circular object is the
diameter
circumference
radius
When you divide c (circumference) by d (diameter), you get a number close to 3.
When you divide the c (circumference) by the r (radius), you get a number close to 6.
2r = d d = r d = c r = c 2

5. pi = http://www.piday.org/million/ is an irrational number
It never repeats
It’s value is = 3.14
is a Greek letter
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6. Circumference, Diameter, and Pi
C = x d or C = d
d = 41 cm
Circumference, Diameter, and Pi

7. Circumference, Pi, and Radius
C = x (r + r) or C = 2r
r= 30mm
Circumference, Pi, and Radius

8. Solve: C = 2 r
r= 15cm

9. Solve: C = 2 r
r= 7cm

10. Grade 8
Learning Goal: I will calculate the circumference of a circle using the formula we generated as a class. Your job
Math Makes Sense Page # 2, 3, 5, 7*, 8, and 9 OR Reflect
Due: Monday November 6th, 2017
2. Coming Soon! Quiz on: -the difference between diameter and radius, calculating circumference