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:

IMG_0538

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

Day91.1

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

Day91.2

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

Advertisements

One thought on “Day 91: Polygons

  1. Pingback: Day 6: Polygons | La Vie Mathématique

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s