Just a quick interactive lesson today that would be perfect as a distraction in any class or as a full lesson in a geometry class. Circles Are Awesome uses the principle, that like a triangle, circles are unique in that they only need three points for you to create one. In Circles Are Awesome, students can learn how this property works and then play with it themselves to create and manipulate their own circles.
From the front page of Circles Are Awesome, have students first select that they want to “learn about circles”. A short 10 page flash tutorial will explain the concept behind using three points to create a circle and how this is mathematically possible. Then once they are finished, allow students to play with circles”. In this section, they can move and manipulate the three control points to create any size circle they wish. Have them increase the number of circles created to illustrate the relationship between all the circles that can exist within the parameters of the control points.
Circles Are Awesome also has a print feature that you can use with the students to have them not only create several congruent circles, but then print their creations to work through proofs and calculations to determine the properties of the circles they created as well as areas and volumes. You could also have them manipulate the points to create symmetrical pairs and then describe the conditions that needed to be met with their control and center points to achieve this. The possibilities of the Circles Are Awesome manipulation page are literally infinite!