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Welcome to my math blog! The purpose of this blog is to help you stay informed about our learning and experiences that have taken place during our math class. I have also included links your child (and you) may want to use in order to supplement math learning in 5th grade.

Tuesday, April 21, 2015

Kaleidoscopic Octagon

Today we visited symmetry.  My students know what symmetry is, however, there were a few terms that I wanted them to learn:

  • Axis of Symmetry - a line through a shape so that each side is a mirror immage
  • Reflectional Symmetry - a type of symmetry where one half is the reflection of the other
  • Rotational Symmetry - the shape can be rotated some amount and still looks the same.
Our activity today came from "Kaleidoscopic Octagon:  Link Geometry, Measurement, and Art" by Karyn Mazo is from a magazine called Challenge that was published by Good Apple in 1999, Issue 83 pp. 14-15.

In the article, the author gives an idea for explaining the math involved in the art as follows:

Kaleidoscopic Octagon

A lesson in spatial logic, patterning, 
geometry and measurement.

The students folded their paper vertically,
horizontally, and diagonally.  Using rulers
they measured from the midpoint of their
folds to construct a regular octagon.
Then the students created patterns which
they reproduced in each section of the octagon.

We followed her instructions to create the octagon.  Please watch our video:  Perfect Octagon from a Square.    Then I had the students create a design in one triangular section of the octagon.  Since my focus is creating reflectional symmetry and rotational symmetry, I required the students to use a "mira" math reflector.  This tool allows the kids to see a reflection of their design in the mira, while also allowing them to see their pencil through the mira in order to trace the design as a perfect reflection.

Here is Mrs. Dittrich's class using the miras to create their kaleidoscopic octagon:

We will finish up the octagons tomorrow.  

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