## Reflection: Checks for Understanding Put It Together and Take It Apart - Section 2: Teaching the Lesson

Building with base 10 blocks is something that students have been doing since kindergarten. They know how to use the ones, tens and hundreds as blocks. They also know the difference between the ones, tens and hundreds, but today I have asked them to take this prior knowledge, and now write a number sentence for hundreds, tens and ones, and then put that sentence together to make a whole number (expanded form).

There were students in the group who built their buildings but then tried to write 3 (for 300) + 4 (40) + 5. They wrote 345 as their total, but they were having difficulty with writing each number out completely. While they maintained the place value as they wrote the total, I did not want to let this go without reviewing with the child the need to write the 300 instead of 3. Later on when they are trying to add and subtract larger numbers, they need to be clear that the 3 does stand for 300 so they don't try to add 3 + 4 + 5 and get an answer of 12.

This lesson seemss simple in the idea that students are building with blocks, but checking that they are seeing that they are adding hundreds + tens + ones (understanding the structure of how numbers are built - MP7), and not just counting how many blocks they have is important for future work.

Simple to not so simple
Checks for Understanding: Simple to not so simple

# Put It Together and Take It Apart

Unit 8: Numbers Have Patterns
Lesson 8 of 14

## Big Idea: Students increase their understanding of place value by manipulating larger numbers.

Print Lesson
5 teachers like this lesson
Standards:
Subject(s):
Math, Place Value, Number Sense and Operations, Algebra, Patterns (Algebra), Model with blocks, addition, subtraction, expanded notation
40 minutes

### Beth McKenna

##### Similar Lessons

###### Taste Test...Gathering Data
2nd Grade Science » Unit 3 - Apples, Pumpkins and Bread!! OH! My!!
Big Idea: Interpreting and analyzing data within a graph is important to share scientific knowledge.
Favorites(4)
Resources(20)
East Wenatchee, WA
Environment: Suburban

###### Odd or Even
2nd Grade Math » Each Number Has a Place
Big Idea: The big idea of this lesson is for students to be able to determine odd and even numbers and why it would be important to understand odd and even groups.
Favorites(20)
Resources(25)
Pepperell, MA
Environment: Rural

###### Place Value to Thousands
3rd Grade Math » Review for Testing
Big Idea: This lesson addresses the foundational skill of place value through modeling.
Favorites(23)
Resources(10)
Phoenix, AZ
Environment: Urban