##
* *Reflection: ELL Students
Presenting Polygons - Section 2: Polygon Vocabulary and Examples

When starting this unit, it's critical that students have a strong understanding of the vocabulary from the very beginning. One technique to scaffold questions about regular and irregular polygons is to set-up a **visual check-list** like in Presenting Polygons Scaffolding Example. To the left of each question you'll see I have students make check boxes with symbols and notations. Students use this to determine if the polygon meets both requirements, that all angles are congruent and all sides are congruent and is indeed regular. If either of these requirements fail, then the shape is not regular. As an added benefit, using the check-list guides students to checking both requirements, and for standardized exams, helps students practice how to justify their work.

Another way to help students with the tricky vocabulary in this unit around polygon names can be seen in Presenting Polygon Helpful Vocab Hint. For hexagon, I tell students that a hex is a curse and the number 6 when repeated is often used in literature for evil. While decagon has the same prefix as decade, hence, this is a 10-sided figure.

*ELL Students: Scaffolding and Vocab Tricks*

# Presenting Polygons

Lesson 1 of 8

## Objective: SWBAT identify polygons and determine the sum of the interior angles for polygons as well as each interior angle measure.

#### Resources

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This activity provides students with an introduction to polygons with a strong focus on the vocabulary related to polygons. This overview will help to provide the basis with which we will discuss more complicated polygons, like parallelograms, in future lessons.

The pair-share at the beginning helps students to work on making math vocabulary their own while using mathematical precise language (MP 6). I have included possible student answers in the resources. You can use them as is to scaffolded student conversation or you may remove the sample answers prior to creating handouts for your students.

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#### Exploration

*25 min*

Students will complete an exploration that will guide them through how to derive the formula for the sum of interior angles in any polygon. Students will use repeated reasoning (MP7) to discover the degrees in multiple polygons, like quadrilateral, pentagon, hexagon and decagon. This video from Khan Academy provides a great overview for you and students, and can be used as a review this class or for absent students.

I have found that the hardest part of deriving the formula is helping students to jump from numerical values (like a 5 sided figure has 540 degrees) to using the variable "n." The (n-2) part is tricky for students but the video does a nice job of explaining this at around minute 5. Once you have the formula, students can then explain each piece of the formula again to a partner or to the whole class. The derivation of this formula leads directly into the next formula, the measure of each interior angle in a polygon.

#### Resources

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The activity/homework can be completed in class or at home by students. These questions focus on applying the formulas for sum of the interior angles in a polygon and the exterior angles in a polygon.

The exit ticket is a quick, formative assessment of students' learning on the sum of the interior angles of a polygon. This exit ticket can easily be extended by asking students to find the measure of each interior angle in an octagon.

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- UNIT 1: Introduction to Geometry: Points, Lines, Planes, and Angles
- UNIT 2: Line-sanity!
- UNIT 3: Transformers and Transformations
- UNIT 4: Tremendous Triangles
- UNIT 5: Three Triangle Topics
- UNIT 6: Pretty Polygons
- UNIT 7: MidTerm Materials
- UNIT 8: Circles
- UNIT 9: 3-D Shapes and Volume
- UNIT 10: Sweet Similar Shapes
- UNIT 11: Trig Trickery
- UNIT 12: Finally Finals