Lesson

# Clip 15/16: Adding and Subtracting Fractions Using a Line Plot Lesson Part 2F

## Overview

After the group continues their work, Mallory calls all the students back to the carpet, preparing to discuss their group’s work with a student from a different group, reminding them of the norms for discussing their ideas, and challenging them to describe all of the plots for problem number three. The students discuss their solving approaches in pairs with each other. Mallory tells students that the total is 15 7/8 and asks what they need to consider before beginning to subtract. A student responds that they need to regroup from the larger mixed fraction in order to subtract 15 7/8 from 16 4/8. She reminds the students that they do not need to start a number line with zero. Students respond as they create the fractional quantities between 15 7/8 and 16 4/8 on the interactive whiteboard. One student shares that he found his answer in a different way: the fractional quantities added 1/8, arriving at the whole number, and 4/8. Mallory praises his strategy. She holds up one group’s large paper and asks the group, “If you have 5/8, where would you plot your new marks?” She invites the whole group to suggest other approaches this group could have tried, with different ways of showing the addition of 5/8. Mallory thanks the students and asks them to return to their seats, cleaning up their materials and turning in their group’s work.

## Teacher Commentary

A lot of the students, when we're discussing how do we create a line plot, they had to refresh their memories about how to rename two equivalent fractions. Oftentimes, they were getting the concept of a line plot and a number line confused. You can create a number line to then create a line plot, but the purpose of a line plot is to plot the data that's been provided to you. So having those discussions between listing the amounts from least to greatest, you don't necessarily need all of the eighths that were included when they listed them. However, if they did include them, it was acceptable. So, I was surprised to see that. And I was also surprised how a lot of students decided to draw pictures or models to support their answers, but at the same time a lot of them did not favor a number line, which is very similar to a line plot. So when they went to go explain or model how they found their solution, they were very hesitant to even try a line plot as a strategy.