## Tuesday, March 19, 2013

### Day 115: Unit 8 - Polygons

To kick off the new unit, I randomly assigned students to groups and had them draw a shape that had either 5, 6, 7, or 8 sides. Once drawn, they labeled the vertices, measured the interior angles and added them up to find the sum.

Thoughts:

• Using a protractor is a still HUGE hurdle. It really shouldn't be, but results were off by over 100 degrees in some cases.
• Allowing any shape seems like it makes the task easier, but students had no idea how to measure a reflex angle, which most likely contributed to our error problem.
• In the future, I might direct students to round measurements to the nearest 5 degrees in the hopes that it will help.
The pentagon had decent results all day, but as the number of sides increased, the errors are compounded, and the results get further and further off. I used Geogebra to try and fill in the gaps and show the ideal case. Some students either noticed the pattern or reasoned through what the relationship between # of angles and total has to be which was surprising.

In the end they all seemed to think it was easy, which is usually a sign that something went terribly wrong.