# Clip 8/16: Problem 3 - 4th Grade Number Ops Part B

## Overview

We carefully chose the problem 26 x 4 for this number talk (mental math) in order to apply the bar model to student thinking.

I think a key element to this lesson is a deep understanding of division. For this particular class at this time, I might try inserting a lesson before the division bar model problem, that asks students a multiplication bar model problem. Once we tried out both, students might clarify for themselves similarities and differences between the two types of stories and the two opposite operations.

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Teacher Commentary

Teacher Commentary

The connection between “times four” and “double, double” gets us on track equal groups and using the bar model. I wish I had also brought back in their idea of “repeated addition” with this. The “break apart” of 104 into four groups of twenty plus four groups of six furthers the bar model example. For time sake, I skipped the second number talk we planned.