Modeling Addition - Opposites Attract, You Know?!

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Students will be able to model addition using chips and a number line.

Big Idea

Do opposites really attract? Read more to find out…


5 minutes

Opener:  As students enter the room, they will immediately pick up and begin working on the opener.  Please see my instructional strategy clip for how openers work in my classroom (Instructional Strategy - Process for openers).  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  In today’s lesson, the intended targets are, “I understand that additive inverses are a number and its opposite. I can model addition using properties of additive integers and chips. I can model addition using a number line.” Students will jot the learning target down in their agendas (our version of a student planner, there is a place to write the learning target for every day). 


55 minutes

Link to Real World:  Modeling Addition Explore Narrative, also a good use of mathematical practice 4. Students will record their responses on the Modeling Addition Notes.

Modeling Addition Practice: Already at their tables, students can find in the resource basket a bag of yellow and red chips. Students will use these chips to model integer addition problems, which ties in mathematical practice 5, using appropriate tools strategically. The red chip will represent a -1 and the yellow chip will represent a +1. I am going to work through the first problem with the students using their help – how many red chips do I need, how many yellow chips do I need? I am using the infinitely cloned chips on the smartboard to model, while students are using the physical chips at their tables. Once we have the problem set up, I will ask students if they see anything we can cancel out, and why. I am hoping to hear the phrase additive inverse fly around – if not, I will add it to the mix.  After a couple examples together, I will have tables finish the examples together, and I will call on students to model the problems on the smartboard. As chips are not for everyone, I will also introduce the number line – I pass out laminated copies of a -10 to 10 number line for students to keep. To model addition using the number line, I am going to have a student help me. In the summary to the previous lesson, students created a clothespin number line. I am going to have a student stand below the -5 on that number line, and walk 4 steps in the positive direction (as the example problem is -5 + 4). I am going to have students do this on their number line as well, using a dry erase marker. Students will see that she ends up at -1, which is the answer to the problem. I will have students do the remaining problems at their tables, and then I will call on more students to “walk” the problems so that we can check our answers! Precision concerning signs is going to be very important – students need to understand that 5 is NOT the same as -5 – which is mathematical practice 6.

Summarize + Homework

5 minutes

Instructional Strategy - Table Discussion:  I am going to pose the question:  when you add two negative numbers, is the sum greater or less than the individual addends?  See my  video for details on how this works in my classroom.  This question will link back to yesterday’s lesson where it was mentioned that the farther a negative number is from zero, the lower its value.  The question is tricky, so I am hoping for some good discussion.  After the discussion I will pass out the Homework.