Modeling
and Explaining
Content
Task Directions
Grade level: Third grade
Content area: Mathematics
Student learning goal: Students will understand
the meaning of the steps in the traditional addition
algorithm by representing multidigit addition
problems with base ten blocks.
Your task: Model the traditional addition algorithm
and simultaneously use base ten blocks to show how
to solve 273 + 152.
Materials: A set of virtual base ten blocks, available on the Performance Materials page, which can be
moved onto, off, and around the workspace
Scenario:
The students in this third-grade class are generally performing at grade level. You have been working with
them on multidigit addition. They have a solid understanding of regrouping when using base ten blocks,
but are struggling with the connection to the standard algorithm. Specifically, you have noticed that they
have trouble understanding the meaning of the numbers that they record in the standard algorithm. You
are going to instruct them on how to use base ten blocks to illustrate the meaning of the steps of the
traditional addition algorithm to solve the multidigit problem 273 + 152.
What will you do?
In this task, you will model how to solve a multidigit addition problem, 273 + 152, that requires
regrouping. You will do this by showing the connection between the standard addition algorithm
and the base ten blocks. Specifically, you will use the language associated with base ten blocks and
the standard algorithm to explain how to solve the problem. You should briefly frame this segment of
instruction by introducing the process, strategy, or technique and explaining its purpose using language
that is appropriate for third graders. In your closing statement, you should revisit the name, purpose, and
key concepts of the process, strategy, or technique. You should do the following:
• Model how to solve the problem using the traditional addition algorithm.
• Simultaneously show how the addition algorithm connects to the problem using base ten blocks to
illustrate the meaning of each step.
• Explain the process as you would for a group of third graders.
• Narrate your thinking and make your decision making explicit to ensure that your students could
use the process for solving a multidigit addition problem that requires regrouping.
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