This week we began looking at combining like terms. On the first day, as the students came into class, I handed each one of them a colored ticket. Each ticket represented a different type of seat at a Giants game. Blue tickets were for box seats that cost $400 each. Green tickets were for lower level sideline seats that cost $200 each. Yellow tickets were for upper level endzone seats that cost $100 each. The question I posed was, “How can we figure out the the total amount of money spent on the tickets?” Students right away realized that they had to add up all of the blue tickets and multiply that amount by $400, add up all of the green tickets and multiply that amount by $200, add up all of the yellow tickets and multiply that amount by $100, and then add up the three amounts. I asked students why we couldn’t add up all the tickets first. Again, right away they said that each of the colored tickets was worth a different value.
Next, I used Julie’s and Nora’s great idea as another visual to show combining like terms using adding and subtracting. I used protractors, paperclips, and erasers, which were items easily accessible in my classroom. Since protractors and paperclips both start with the letter “p”, the students decided to use the letter “c” to represent the paperclips. As students placed items into the bag or removed items from the bag, I wrote the expression on the board as each student wrote the expression down on their small whiteboard. When I asked what was in the bag, only a few students wanted to put all of the variables together as one term. Not bad! They loved the activity!
We finished by making a frayer model to define like terms and added this to our interactive notebook.