## Reflection: Checks for Understanding Where is the Question - Section 2: Teaching the Lesson

We concentrated today on finding the words in word problems that help us to know whether to add or subtract. The students did a great job finding the words, and were able to determine if they needed to add or subtract.

But, then they were not careful with the computation. One group gave 55 as the answer for 85 - 35. When questioned, they said they took 3 away from 8 to get 5. (I asked if this was tens or ones and they said tens.) Here students were not attending to the precision of solving the problem (MP6)

Then they told me they subtracted 5 from 5 and got 0, but they wrote 55. When I pointed this out they had trouble seeing why the 55 was different from what they told me.

I saw similar mistakes with other partnerships. I think I need to teach students about checking their work to see if it makes sense.

I realized that determining the operation was taking a lot of the “brain” focus in this activity.  Also numerical sense making is  not yet in place.  Although one of my goals is for students to make sense of the problem (MP1), and persevere in solving it, I realized that students had trouble maintaining the focus and stamina to do both. When the focus is only on manipulating numbers, they are in the “groove”, but now like are being asked to juggle two things - determining operation and manipulate numbers. It will take additional practice for them to be able to maintain the focus throughout a 2 part problem such as these.

FInding the Words, Forgetting the Math
Checks for Understanding: FInding the Words, Forgetting the Math

# Where is the Question

Unit 17: Getting Better at Addition and Subtraction
Lesson 1 of 12

## Big Idea: Students can perform addition and subtraction within 100 using a variety of math tools, however, determining which operation to use is a higher level thinking skill that is being introduced in this lesson.

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Standards:
Subject(s):
Math, Number Sense and Operations, addition, reasoning, word problems, Operations
65 minutes

### Beth McKenna

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