Lesson 11

Circumference from Area / Area from Circumference

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SWBAT determine the circumference of a circle given its area and vice versa

Big Idea

This is a simple lesson that eradicates simple mistakes when finding the circumference from area or vice versa.

Teacher Model

10 minutes

Guided Practice

10 minutes

The students will work through the guided practice problems using their notes and partners as a resource.  These problems mirror the example problems, but also  include problems where 3.14 is used for PI.  I will monitor student work looking for common problems to bring to the attention to the entire class. 

Independent Practice

20 minutes

Students now work independently on the next set of problems.  These mirror the work just done, so students who are having difficulty should have several models to refer to.  If I am asked a question, I will first point students to those models from the examples or guided practice. 


The extension problem is included to provide another “real-world” area and circumference task.  Part I requires students to explain their thinking (MP3) .  It requires an attention to precision (MP6) as students must realize that the radius is not the same at all points on the walkway.


Exit Ticket

5 minutes

Students take an exit ticket.  The first two problems are multiple choice to catch common errors through the distracter items.  Problems 3 and 4 are open ended.