Monday, September 30, 2013

The Proof is in the Pudding...or the Proof Practice Book!

The most recent stop on my journey into the world of teaching Geometry was introducing proofs.  Let me tell you, this is a giant shift in thinking from my Algebra 1 roots.  Same steps, new justification.  Lovely.  The good news is, my kids seem to really get it (at least so far!)

Even though I have 8th grade Geometry students (which means they are SUPER advanced) I decided to start into proof world with baby steps.  I gave a quiz in the first half of the hour over previous material, and then had my students glue the Properties of Equality into their math folders.  You can see the completed notes in the picture below.   Side note: fill-in-the-blank notes are working like magic for this class!

The next day I decided to see what my kids could do on their own.  We did one two-columned proof together as their First Five, and then I had them work in groups of three to complete 8 more proofs.  They had to fill in the reasoning behind each statement, and then send one group member to check their answers.  They only got one proof at a time, so once they had it right they picked up the next proof.  I had each one on different colored paper so they could tell them apart.  

Here is what the Proof Practice Book looks like (I forgot to rotate a few pics...sorry):

This is the inside of the practice book.  I had the statements already written, and the students filled in the reasons using their notes from the day before.

This is a student sample for one proof:

I cut manilla folders in half for the answer keys.  Each page of the practice book has the solution to the proof on one side, and directions on which color proof to get next on the other.  This made it easy for the kids to check their answers AND to know what to do next.

Here they are, spread out and waiting.  This worked PERFECTLY because each group could work at their own pace.

In the end this was an awesome activity.  The kids stayed involved the whole time, and worked together whenever they got stuck.  I told them that it was their responsibility to make sure that each group member understood the proof, and they took that seriously (yay!).  I'm glad that it worked well, and that the kids were able to figure a lot of it out on their own.  


  1. Would you be willing to share your documents with us?

  2. Do you have the first image on this page as a document that you could send to please?