## Thursday, September 24, 2015

### Day 18: Expression Mat Intro & review of slope

Today's estimation was the amount of staples in a mini staple strip. Some students used their own personal staplers to make accurate estimates. I complimented students who used the regular staple strip in the picture that was 210 staples and thought the mini one was 1/4 or 1/5 of the big one. Then they divided. Great reasoning. I gave out raffle tickets to student who did their homework and were self correcting it after the estimation.

In Common Core 8, students brainstormed the meaning of minus: subtraction, negative sign, and the opposite of a number. They reasoned -(-3) is positive 3. I asked them why and they said 2 negatives make a positive. So, I said, so what's the opposite of -3? 3. I wanted them to move away from some rule they heard and think about the meaning.

I introduced students to the positive and negative sides of the tiles. I asked them what the tiles all had in common and they all had a red side. So, they all have a negative side, that red side. Students grappled with the fact that 3 red unit tiles in the positive region is -3 and 3 positive tiles in the negative region is -3. Unfortunately, prior teachers told students the red side was the positive side. I discussed this with the students and the teachers.

One student, originally from China, told me that in China, in the stock market, red means it's positive and going up, and green means it's going down. Apparently red is good luck and a popular color in China, while green is bad luck. It's the exact opposite of our American understanding! I said that's weird. Then I caught myself, told the class I had said this after sharing his story, and said that I wasn't being respectful of the differences between our cultures and that just because I'm not used to it does not mean it's weird.

I brought up the online algebra tile tool and had volunteers show me two ways to show -2x and two ways to show 3x - (-4). Great conversations.

Then I did the community building I learned from math camp this summer with CPM. It had amazing results. For example, I had all students stand up in the middle of class. Stay standing if you have a brother. Stay standing if you like babies. Stay standing if you enjoy penny boarding, and finally stay standing if your birthday is April whatever. Then one student is standing, and I asked him to explain what penny boarding is and why he likes babies. He said it's a mini skateboard and that babies like him and he's good with him. We gave him, and every student in each class that was left a 3 second clap. Students loved it so much they wanted to do it again. I said every week we will do 1 person.

Then students setup expression mat drawings to represent expressions 2 ways. They did not finish and we didn't have time for closure so we will continue tomorrow. I noticed students needed reinforcement on shading for positive and unshaded for negative. They also needed to be reminded the x tiles were rectangles so don't make them squares and make sure you label them x.

Tomorrow is skills 3, 4, and 5 on the assessment. Percent error, proportional relationships, and combining like terms and perimeter of algebra tiles.

In accelerated students once again refreshed on slope. They will refresh on y=mx+b tomorrow. Students are continuing to work on their study team voices, because they can be too darn loud sometimes when working in groups. It's a work in progress.