Mirror images

This past week, we studied congruency and symmetry. Congruency tends to be relatively simple for the kids. Same size, same shape. That's pretty easy to remember. What often throws them is when the shapes are rotated. Especially when the shapes are triangles.

But symmetry really throws them for a loop. When I would draw a shape and ask how many lines of symmetry it had, several of them would just count the sides and give me that answer. Several would always say 2 (vertical and horizontal). And several would find lines that weren't symmetrical at all.

Diagonal lines are especially hard for the kids to judge. Though I've emphasized to them that they can and should TURN their paper, to make the line look vertical, they usually don't. Also, they confuse it with congruency, so if the two sides of the line are the same size and same shape, they go with symmetry. Even if the two sides aren't mirror images. For instance, the diagonal line of a rectangle DOES split the rectangle into two congruent triangles. However, this line is not a line of symmetry, because folding the shape on the line would not yield a perfect matchup.

Friday's test results weren't too bad, but there is clearly still a lot of work to be done, especially in some dire cases. (Where kids still don't even know their basic shapes.)

At least I haven't had anyone yet this year call it a "line of cemetery."

Carnival of Symmetrical Democracy

First, a couple of links of the week:

This week's Mr. Teacher column on education.com is titled "Democracy in Action" (my apologies to John Stewart). I asked my kids to explain to me who they voted for and why in our recent mock election, and their answers are definitely worth reading.

This week's Carnival of Education is hosted by the Core Knowledge Blog, and the dude's got a nifty little theme going. All of us who contributed were (theoretically) tapped for cabinet posts in Obama's new government! Since there is no Secretary of Ketchup, I've been shortlisted for Secretary of Energy!

Today, I handed out piles of rubber bands to my kids during class. You may be asking yourself why on earth I would do something that is akin to shouting FIRE in a crowded theater or entrusting foxes to guard a chicken coop. Because we're working on symmetry, of course, and the rubber bands were for use with the geoboards.

I'm quite pleased because not once did I hear any of my kids use the phrase, "Line of Cemetery," as I often have in the past. And after a very stern warning that they would be prosecuted to the fullest extent of the law if they should even THINK about snapping the rubber bands at each other, they loved making shapes and finding lines of symmetry with the equipment.

We had 2 teachers absent today. One had a scheduled sub who called in sick, and the other was last-minute so no sub could be obtained. That left us with 4 teachers and 125 kids. At first, the office wanted me to split both classes up amongst the 4 of us. I balked at that, and thankfully someone else stepped in to cover one class. Still, we had to split up one class, giving each of us 24-26 kids in rooms that are roughly the size of a gas station restroom. I had to go into one of the other rooms to get some more chairs, as I didn't have enough desks for all of the kids to sit at.

I understand we'll be going through the same dance tomorrow as well. Maybe I should get rid of all of the desks in my room and just let the kids sit on the floor.

Except then the kids wouldn't have anyplace to stick their gum...

Another worthless (?) Mnemonic

OK, so maybe I'm just spinning my wheels here, but I tried another silly memory device out on the kids today.

First I asked who liked the movie Toy Story. Of course, everyone raised their hands (including me). So then I made sure that they knew who Buzz Lightyear was. Which they did.

Then I said, "And you remember that part in the movie where he shouts…

‘To the SYMMETRY and beyond!’

And then he hits the little red button on his chest, and his wings pop up, exactly the same on both sides, just like he has a line of symmetry?”

Of course the kids’ first reaction was to argue with me -- "THAT'S not what he says!!!”

But they still thought it was pretty funny and were repeating it a few times.

So during our after school tutoring session, I asked my kids if they could show Mrs. Educator our new way of remembering symmetry, what we could say, and nearly everyone of them busts out with, "May the fourths be with you!”

SHEESH!

I had to bite my tongue not to utter another Buzz Lightyear-ism—

“You are a sad, strange, little man, and you have my pity.”