You might precede Lab 11.8 with a reminder of the formulas for circumference and area of a circle, with the help of this animation.
- You can use these slides (more animation!) before, during, or after the Lab:
 - html with narration (does not work on Safari)
 - html without narration
 - Keynote
 - Spoiler alert: the slides answer questions 1-3 of the Lab.
 
Here is a colored and expanded version of the figure in the Lab: