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?

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…

. Minds On: Measure the distance around different circular objects. ObjectDistance Around (cm) Radius (cm) Diameter (cm) Stool BUCKET54.5cm9.5cm19cm White board maker 5.7cm0.7cm1.4cm Paint22cm3cm7cm Elephant skin ball 55cm27.5cm55cm Broom handle 7.5cm1.5cm3cm

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

100+more Apple Pie Related images: View more Images may be subject to copyright.Send feedback pi = is an irrational number It never repeats It’s value is = 3.14 is a Greek letter

C = x d or C = d d = 41 cm Circumference, Diameter, and Pi

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

Solve: C = 2 r r= 15cm

Solve: C = 2 r r= 7cm

Grade 8 Learning Goal: I will calculate the circumference of a circle using the formula we generated as a class. Your job 1.Math Makes Sense Page # 2, 3, 5, 7*, 8, and 9 OR Reflect Due: Wednesday November 11, Coming Soon! Quiz on: -the difference between diameter and radius, calculating circumference