## Thursday 26 November 2015

### MPM2D - Day 54: Factoring, Day 2

The algebra tiles were waiting on students' desks as they walked in this morning, but as we had not finished what we started yesterday, the tiles had to wait. My students were not impressed with common factoring binomials. Even with pumpkins and happy faces.

And then I really made things worse with this:

We did a little work on the whiteboard to try to figure out how to deal with this case. They game me numbers, we worked out x - y and y - x. We talked about what was the same and what was different and then I asked how I could get the value of x - y given the value of y - x.

Of course multiplying by -1 will change the value, so how can we overcome that? Multiply by -1 again! Yeah, I lost a whole lot of them at this point. I know I did. I decided to let it sit with them for now and come back to it next week for a second try...

But then (I am so cruel) I made them factor by grouping. This is all leading somewhere, I told them. I'm not sure they believe me!

I think they were all really thankful to move on to "playing" with the tiles. We expanded, we factored; all was good again. I emphasized that they need to make a rectangle and that the x^2 tiles will be in one corner, while the unit tiles will be in the opposite corner.

A couple of examples for them to try:

Then we added negatives to the mix. Here is the link to the Gizmos activity. I click on "new" until I get a trinomial with negatives. I find this quicker for introducing the concept of adding zero pairs. And then they tried a few that were not monic.

I think they understand the how and the why of factoring trinomials. They will spend tomorrow practicing many more questions with the tiles and (hopefully) will start to notice some patterns emerging.

Here is today's homework.