Monday, November 03, 2008

Teachable moments: Symmetry

The fine young gents and I just spent twenty minutes dissecting the alphabet. Which letters can be divided symmetrically? We spent almost five minutes on "O" alone. Second-grade gent, all on his own, figured out that "O" can be divided symmetrically in "more than a googol" ways, which started a short discussion of infinity, which the gent in turn related to earlier "half of a half of a half of a half...." math play.

I thought the alphabet would take five minutes. They surprise me this way sometimes. An activity I'm sure will be a hit falls flat. A simple activity I throw in as a filler sparks a lengthy discussion. The point is not that I have math geniuses, by the way. Nor am I a math genius or a teacher extraordinaire. It's a fairly simple activity in which kindergarten gent was able participate easily, and I mostly sat there and asked questions. The point is that by taking extra time to really explore the idea when they were engaged and interested, we had the opportunity to explore new ideas.

Alphabet symmetry: Go low-tech, and print the capital letters on a sheet of paper from the recycle bin. Draw a line through each letter to divide it so that both sides are matching. Look at the halves. Do they have to be facing the same direction to be the same shape? Are they still symmetrical if you have to turn the pieces? What happens if you draw a line here? Or here? I draw my "U" with a tail. Is there a way to change it to make it symmetrical?

Or print out this worksheet: Symmetry in the Alphabet

Or go high-tech. For a more in-depth exploration of symmetry, try this webquest, Symmetry All Around, to learn about point symmetry and rotational symmetry, create a snowflake or a quilt block, or to find more links to activities for teaching symmetry.
On another math note, Julie K in Taiwan left us a great tessellations link in the comments on the tessellations post. It's too good to miss. Visit Tessellation Town! Don't miss the rest of the site. Visit for lots of math fun. Thanks, Julie!

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