## Reflection: Checks for Understanding Time to Practice - Section 2: Practice Centers

If I had a dime for every time the students wanted to jump from using the manipulatives, to carrying out double-digit subtraction on paper without the blocks, I would be a rich second grade teacher indeed!

Students in second grade often think that the blocks are for babies. They don't realize that the blocks are giving them a chance to understand and demonstrate foundational addition and subtraction concepts.

I reviewed student work to assess understanding.

Today students worked on adding and subtracting with blocks. I had students in that small group with a parent for support. Several of the students tried to do the work without the manipulatives. They said they could do it without, and they switched the numbers and subtracted in columns without grasping the concept. For example, a child subtracted 80 - 27 and write 67 as an answer. She had written the problem in columns but then subtracted the ones and said 7-0 = 7 and then did the tens and had 8 tens - 2 tens is 6 tens, so the answer was 67.  The students who carried out the problem with the base 10 blocks all were able to get the answer correctly.

It is hard to teach addition and subtraction with regrouping. It is something that has to be revisited over and over with manipulatives. Do not rush to the algorithms for addition or subtraction until students really grasp the concepts involved in regrouping and can demonstrate their understanding using the manipulatives.

I Don't Need the Blocks
Checks for Understanding: I Don't Need the Blocks

# Time to Practice

Unit 11: The Numbers Are Getting Bigger
Lesson 7 of 15

## Big Idea: Students need time to practice new skills. They have been introduced to addition and subtraction of double-digit numbers. Today's groups will allow for practice of these skills.

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2 teachers like this lesson
Standards:
Subject(s):
Math, Manipulative Skills, Number Sense and Operations, addition, subtraction, base ten
55 minutes

### Beth McKenna

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