Tuesday, August 31, 2010

Beginning Geometry Postulates

Today was the first day my geometry students would see postulates. The book starts with the standard "through any 2 points there is exactly one line", etc. I didn't want to just present them and state their significance, so I tried something new. I handed out this True/False sheet and had the students work in their groups to determine which statements were true or false while I walked around. I heard some great discussion, and I gave them about 7-10 minutes. Not every student got every one right, so that makes me glad I did this. I'm guessing if I just presented the postulates and explained them, I'd get a bunch of nods and, "oh yes, we get it" expressions when in reality, maybe they didn't.

Here's the sheet:

By the way, 5 of them are True and the rest False (as if you didn't know :) ).


  1. I really like this idea. It's just too bad we've already covered most of these. :-) Next year though...

  2. Great idea--I hate going over this stuff the usual way. If I have a geometry class, I am going to use it. Thanks for sharing.

  3. Stacy: I'm wondering if you still give it to them if they'd get the true ones correct. Probably, but ....

    Pissed Off: That's exactly what I was thinking. I've been talking at them a lot lately with all the definitions and such, so this was a nice break. At the end, we highlighted the true ones and I had them tape the cut sheet in their notebooks with a header of Postulates.

  4. I created a version of this activity for points, lines, planes, but I had the kids mark "always true, never true, and sometimes true." They had to also draw different instances if they think it's only sometimes true. It was a time-consuming but (I think) worthwhile activity!

  5. I wish I was teaching Geometry this year! I would love to try this activity... I think that I'd try it Mimi's way because "sometimes, always, never" questions are often difficult for students. Thanks for the "group" idea!


  6. Mimi: I love the ASN questions. Those really make them think.

    Ms. Cookie