## Reflection: Problem-based Approaches Adding Three-Digit Numbers with Regrouping - Section 1: Problem of the Day

Prior to this lesson few of my students had seen three digit addition problems that require regrouping.  Despite this, I chose to let them puzzle with a problem of the day instead of simply giving them a strategy and having them mimic my strategy.  When I presented this problem I saw students respond in a variety of different ways:

1) Students drew hundreds, tens, and ones or used hundreds, tens, and ones blocks to represent the problem.

2) Students drew an open number line.

3) Students used cubes bundled in groups of tens to solve.

4) Students used invented algorithms (i.e: 100 + 30 + 200 + 29 or 30 + 30 + 100 + 199=)

5) Some students dove right into regrouping and solved the problem using the same kind of regrouping strategies that we had discussed when we learned about adding two digit numbers together.

Allowing students to solve this problem in creative ways allowed students to problem solve and begin to develop a conceptual understanding of how to solve these more advanced problems.  Further, it allowed students with various levels of mathematical confidence/understanding to access this problem and understand what they were doing (i.e: my students who struggle more used cubes bundled into groups of tens to solve instead of being "forced" to  learn the trick of regrouping , a concept that they might not understand right now.)  Allowing students to use a strategy that works for them allows them to accurately solve these kinds of problems and attend to precision (MP6).

Problem of the day
Problem-based Approaches: Problem of the day

# Adding Three-Digit Numbers with Regrouping

Unit 6: Three-Digit Addition and Subtraction
Lesson 3 of 13

## Big Idea: Students identify, use, and share strategies for adding three-digit numbers that require regrouping.

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14 teachers like this lesson
Standards:
Subject(s):
Math, Differentiation, Number Sense and Operations, addition, regrouping, turn and talk
45 minutes

### Caitlin Vaughan

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