Wednesday, April 27, 2016

Intro to Factoring Trinomials (a = 1)

My CP Algebra 1 classes have started factoring trinomial today, where a = 1.  I have always enjoyed factoring trinomials personally, however many of my students don't share my enthusiasm.  It baffles me that they don't enjoy this puzzle of sorts.  "Can you think of two numbers that add to this and multiply to that?"  I believe they don't see it as a puzzle because I don't present it as a puzzle.  I changed that this year.

I started class by giving each student an index card.  I asked them to write their name on the lined side and two integers from -12 to 12 except 0.  Like this:

Next I told them to flip the index card over to the blank side and write the sum and product of the two numbers like this:

Once they were all finished I took the time to walk around the each student and make sure he/she added and multiplied correctly.  It only took a minute but I did find a few mistakes.

Then the fun begins.  Each student was to hold his index card so that the Add/Multiply side was showing and the two original numbers couldn't be seen.  All students were asked to stand up and go from person to person and try to figure out their puzzle.  In other words, "What were their original two numbers?"

The students really seemed to enjoy trying to figure out each other's puzzles.  They especially liked when they stumped someone.  

Overall, I think the activity was a success.  But I did find this stink-poop drawing on the board after class so I'm not so sure anymore.


  1. I absolutely love this idea as an introduction to factoring and will definitely be using it next year! Thank you so much for sharing!!

  2. I'm thinking that it would be stink-poopy to poor souls who didn't know their times tables... yea, I always liked this kind of puzzle (and it really nailed down my tables, and things like 16 x 3 being 48).