Reflection: Pacing Doubles Plus or Minus One - Section 3: Independent Practice


Within a few minutes of beginning the independent practice I realized that I had made a leap that was too large for most of the students to make. The warm ups and the game had gone so smoothly with doubling and adding or subtracting one, that I thought an independent practice where students identified whether they were doubling and adding or subtracting one would be relatively easy.

I was so wrong! The students could count to solve the problems but they had no idea how to determine if they were using a double or not. Most of them clearly were solving the problem without doubles and the idea of a double just confused them. So much for good intentions of providing kids with a new strategy.

I tried to stop the independent practice and reexplain what the paper was asking, but even with that I could see that most of the students had no idea what I was asking so I stopped the work. 

I asked students to put the papers in the finished work basket (even if they weren't done) and to come to the rug. I told them that I had made a mistake because I had given them a page that I had not really explained. I told them I was sorry if they were confused and that we would back up a little and I would try to explain the idea again.

I drew a dice with 4 dots on the board. I asked for a student to draw another dice to double four and the child drew a dice like mine. Next I asked someone to come up and write the number sentence for adding the two dice. They did this easily. Next I said, what if I added a dot to this die, now how many dots are there on that dice. The students quickly said five.  I asked if anyone could write the new number sentence. A student wrote 4 + 5 = 9. I asked if this matched the dice and everyone agreed that it did. I asked how it was similar to the first problem. The students said it was almost like it but there was a five instead of a four and an nine instead of an eight.

We talked about how when we added one to one side of the sentence, we had to add one to the other side to keep the two sides equal or balanced. I used my body as a balance to show what I meant.

We did several similar examples and I stopped there for today. I had made too large of a leap, so I moved back to where the work had made sense for the students and started to build a new bridge for them. I will do more of this bridge building in the next lesson, which focuses on how doubles always come out even, but doubles plus or minus one always come out odd.  

  Pacing: When Disaster Strikes STOP
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Doubles Plus or Minus One

Unit 2: Adding and Subtracting the Basics
Lesson 9 of 18

Objective: SWBAT use what they know of doubles and partners of ten to add or subtract numbers that are one more or one less

Big Idea: One of the Four Critical Areas of 2nd grade math is the application of understanding of models for addition and subtraction. An efficient way to do this is to develop strategies built on what students know.

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