## Sunday, July 21, 2013

### Geometry: Polygons and Angles in Regular Polygons,

I heavily relied on the CSCOPE curriculum, End of Course prep book, and online resources to guide me through this unit. This is my first year to get this far journal wise and thoroughly teach properties of two dimensional figures.

Pg 1. Unit 7 Properties of Two Dimensional Figures

When I get the whole Youtube thing figured out, I will try and share some paper-folding lessons I've learned in workshops and used in my classroom. They strongly support the unit on two dimensional figures and they are fun!!

Pg 2. Polygons

This is an unusual foldable, but I love how it organizes the concepts I'm trying to get over to my students. It's folded into fourths. The right side is folded two times into itself and the the left flap folds over top to the right. (Sorry if this explanation is terribly confusing; hopefully the pictures make more since.)

Again, there's some gray area as far as complex polygons go, and I informed my students as such. Any opinions or suggested resources, please share.

Next year, I plan to use color to compare corresponding categories.
Complex vs Simple
Concave vs Convex
Irregular vs Regular

Pg 3. Angles in Regular Polygons

I enjoy teaching this lesson because students need multiple ways to determine angles and experience deriving the formulas from building patterns.

We started with a large polygon on the front and illustrated what is considered the interior and exterior angle. Next, I asked them to make a conclusion based on what they know. They concluded that the interior and exterior angles are supplementary! We added that statement to the top. We then went to the inside and completed the gigantic table to derive the formulas. We finished by writing the important formulas and ideas on the front inside the large polygon.

Students struggled with remembering the formula for the measure of an interior angle. They found another way - determine the measure of an exterior angle (easy), and subtract the measure of exterior angle from 180 to determine the measure of the interior angle. A much longer process (to me), but I was so excited that they could figured an interior angle measure out based on concrete prior knowledge.