Proof of the Pythagorean Theorem
Before moving anything around, read what each number tells you:
Top left number tells you the length of segment K1G
Bottom left number tells you the length of the segment AG
Bottom right number tells you the length of the segment XY
The center number tells you the area of the center square.
You may now move around points B and G. You may also move the slider back and forth. When the slider is all the way to the right, you will notice the appearance of two squares. Each number displayed in the center of the squares is the area of that square.