## Reflection: Organizational Systems Investigating Special Quadrilaterals - Section 2: Notes on Polygons

Because the topic of transformations is such an important part of geometry, and because our definition of “congruent” has shifted from “all corresponding sides and angles are congruent” to “completely covering another figure after sliding, rotating, and reflecting,” I knew that I had to change all the language I would use when talking to students.

While giving notes on polygons, I decided to use my hands to model some of the ideas I was trying to explain with regard to congruence.  For example, I brought my thumbs and index fingers together to form a kite-like shape; I then squished my fingers outwards to form another kite-like shape and asked students to explain whether or not they thought both quadrilaterals were congruent.  I then squished my fingers inwards and again, asked whether this quadrilateral was congruent to the first and why.    I heard some students say, “they aren’t congruent because even though the sides stayed the same, the angles changed, which means the shapes won’t perfectly cover each other.”  Right now, as it is the fourth week of school, this idea of congruence sounds spot on to me.

Applying a Transformations Lens to Polygons Vocabulary
Organizational Systems: Applying a Transformations Lens to Polygons Vocabulary

Unit 2: Introducing Geometry
Lesson 4 of 8

## Big Idea: In this hands-on investigation, students will explore properties of special quadrilaterals and ultimately come up with a minimal defining list to differentiate them from one another.

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Subject(s):
Math, Geometry, deductive reasoning, definition, basic properties
95 minutes

### Jessica Uy

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