Circles, Circumference, and Pi

When learning about circles, we first read the books:

"Sir Cumference and the First Round Table" and "Sir Cumference and the Dragon of Pi."  Then we measured the circumference, radius, and diameter of lids, plates, and embroidery hoops. Then the girls had to figure out how much ribbon would exactly go around a can by using those measurements.

Then we measured the circumference of an apple and figured out what the diameter would be if we cut it as shown in this picture. Then we measured to see if we were right.

Then we had fun with tortillas. The girls then folded over a tortilla to form a semicircle. Then we had to figure out how to find its perimeter. Then they folded it over again to make a quarter circle. Then they figured out how to find that perimeter. Then we learned how to find the perimeter when part of a circle is attached to another shape. We cut the quarter circle out and turned it around to make a square corner attached to the rest of the circle (like a tear drop). 

The best part of learning about pi was celebrating with real pie.