Day 91: Polygons

Geometry started talking about polygons today.

I broke the class into groups and had them sort these polygons from least to greatest number of sides:


Every group had the first 8 or so correct. After that they were everywhere. There were some interesting discussions on what polygon had the most sides and what that number was. Some said 20, other said 90.  Also, some great discussion on how to sort/classify.

After, they started working towards discovering the Polygon Angle Sum Theorem


They copied down the table and started working. Again, some very interesting discussion/methods of completing the table. Some based it on recursion others saw it as linear.

In the end everyone settled on 180(n-2). Why this worked though was another story. Eventually they got it and found out (n-2) is the number of triangles each polygon can be broken into.

For example


Today was a lot of fun, it sure beat just telling them the rule and practicing 30 problems after.


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