My summer begins Friday. One of my goals over the summer months is get my thoughts down about the mathematics behind the applet below. It is stunningly simple, but it is the details I want to make clear. So, I present it to you as a sort of summer inquiry activity for teachers. As you move the green points around and as you drag the purple-ish circle around and change its radius, what happens?
Follow Up: After sharing this with some of my students after one of their exams, they expressed a desire to be be able to place points and draw lines, so I updated the applet to reflect their wishes.
I was pleasantly surprised over how much time my students spent with this applet and the quality of their observations.