## Tuesday, September 22, 2015

### Day 16: Combining like terms. Domain and range.

I taught like this half the last period after our fundraising assembly...

Students estimated the number of staples in a staple gun strip. Only a few students reasoned that the staple gun strips were thicker so they must be less than 210. A lot estimated over 210, the amount in a regular strip. This was a bit concerning so I definitely wanted to open it up to everybody to see if they had compared them.

I passed back the 2nd mastery assessment from Friday. A lot of students improved on the percent error skill. I also showed examples of student work that fully explained why the relationship was proportional (0 bowls for 0 dollars, passed through origin, straight line, constant rate of change, etc.) Friday will be skills 3, 4, and 5, and students will be assessed on combining like terms when given an expression and when given algebra tiles next to each other. I was happy to hear some students wanted to be retaught and retake an assessment, and said I would do so on Friday with about 5 of them.

Periods were shorter so students only got through 4 expressions, matched like terms orally, and setup the first algebra tile picture. Tomorrow they will take out the tiles, build it, draw it accurately, label the sides, write an unsimplified expression, then simplify the expression.

I liked how Yssa put triangles around like terms, squares around other like terms, and used circles. I pointed this out and she said that Mrs. Ko had shown them that last year. I wanted to honor the fact that she was using a strategy she had heard of before. I also encouraged students to color code them to see them similarities in the like terms (same variable and exponent).

In accelerated, I also passed back the assessments and they filled out their skill sheets. I had students figure out where they left off last period, and then checked in on each group. I could see that they were trying to explain to each other and grapple with it. Once they had enough productive struggle, and had asked some good questions that got students in the right direction, we reviewed what they had understood so far.

I asked students how we could write the domain if it was between -1 and 3. I asked what variable the domain represents (x). So, to scaffold the problem, I drew a number line with -1 and 3 on each side, and x in the middle. I asked how we can say that the domain is between these numbers. That got some students thinking of inequalities, and Zoe came up with how to write the inequality. We also discussed range. I asked them how the inequality would change. They said it would be y instead of x.