# Clip 2/13: Pre-Lesson Part 2

## Overview

Before her lesson, Erika Isomura discusses her plans for her teaching with her friend, colleague, and math coach [Mia Buljan](http://www.insidemathematics.org/common-core-resources/mentors-of-mathe…). Erika shares that her fourth graders are largely working on “a lot of foundation. Do they understand equivalence, do they even understand what fractions are. Do they understand the purpose of the numerator, the denominator, where they are on the number line. The fact that oftentimes when we’re working with fractions to start, we're usually talking about things that are less than 1, and that's really confusing to them. That idea of something can be less than one and is not negative.”

## Teacher Commentary

ERIKA ISOMURA: My fifth graders were deepening their understandings begun the year before because they were now doing all the operations, they were doing addition and subtraction with unlike denominators. I wanted to have my students explore and interrogate their assumptions and convictions about how operations and fractions work.

I talked with Mia Buljan about using a bar model as opposed to an area model, leading up to the card sort in the documented lesson, and my rationale for selecting particular mentor problems, similar in structure to ones they had done before, with quantities that the students had previously worked with.

I sequenced the bar model representations to increase my students’ understanding of how the model could be a useful strategic tool in problem-solving, and to see if they could then apply the model independently to novel problems. I hope my students will be able to take a decontextualized problem, for example on a standardized test, and link it back to a real-world experience in which they linked a scenario and a strategy.