# Gizmo of the Week: Circumference and Area of Circles

Friday March 14 (3.14) is Pi Day! Get ready with the Circumference and Area of Circles Gizmo, which has been recently updated with new lesson materials.

In this Gizmo, students can set the radius of a circle, and then use the provided geometry tools to measure the circle’s circumference. The area of the circle can also be displayed. Students can quickly discover that the ratio of the circumference to the diameter is always equal to the same number, pi.

Don’t forget to do the real-world experiment too. Have your students use rulers and string to measure the diameters and circumferences of as many circular objects as possible—pot lids, Frisbees, plates, and of course pies!