Clip 7/16: Adding and Subtracting Fractions Using a Line Plot Lesson Part 1F

Overview

Mallory’s 5th-grade students continue working in groups on the problems for the task, as she circulates around the room. She asks them to share their ideas and encourages them to test the various strategies offered by the group members. Mallory reminds her students to engage in discourse with each other: “Can you restate what you’re doing? Can you talk to him? What did you discover?” She challenges the groups to draw a picture to justify their strategies and their solutions, working collaboratively as they go: “If you’re stuck, I need you to talk to your team.”

Teacher Commentary

When I went to a particular group, they had tried multiplying three-fourths times four, and one of the students had placed twelve down and then another one of her peers decided to record twelve-fourths.

When I asked, “Is it going to be twelve-fourths or twelve?” she then didn't necessarily understand. She thought she was wrong. She wasn't necessarily wrong, but there is a major difference between twelve as a whole number and twelve-fourths, which is equal to three. So I needed her to reason through the difference between just placing twelve as our solution versus twelve-fourths, which is actually, when you show the model, you're only shading in three holes. So she easily was able to recognize that mistake after the discussion. But if we were just to leave it, she would just write down twelve was her answer and ultimately be incorrect.