Math Activities: Lines of Symmetry

Houghton Mifflin


Software Used:

From 2002 to the end of 2003, I worked as a freelance interactive designer. During that time, I had the opportunity to work for Houghton-Mifflin creating online math activities that mirrored the end of chapter activities in their school text books. While much of the activities were strait forward arithmetic that require just a few input fields, every now and again I would get to work on an activity that would really challenge me. My favorite one was building the “Lines of Symmetry” activity.

I solved this problem by setting up two “listening” points on the shape along each point of symmetry. When the user drew a line, if that line hit both listening point, the flash movie would flag that symmetry point as being found. Folding the shape was also a challenge. Since flash did not allow masks to be programmatically placed and rotated, I needed to place and rotate the shape around the mask and then offset the shape’s parent by an opposite position and rotation. I then made a duplicate of the shape, and positioned only the folding area outside of the image mask. Then it was simply running a x-scale animation from 100% to -100% to simulate the folding.

Below is the finished product. It requires the Adobe Flash plug-in and will not display properly on all devices.