Choose a Scale (IM Grade 3, Unit 1, Lesson 6)
Task
Lesson Purpose The purpose of this lesson is for students to consider the advantages and disadvantages of various bar graph scales. Lesson Narrative This lesson allows students to choose and create the scale for their bar graph and reflect on the advantages or disadvantages of their choices. Through the work of the lesson, students notice that they can choose a scale based on the numbers in the data set and that the scale can make a graph easier or more difficult to read (MP6).smaller fraction. How Tuva Enhances this Lesson In this activity, students go beyond simply drawing bars—they learn how to select an appropriate scale for a bar graph based on the data. Third graders often spend most of their time and cognitive energy on the mechanics of hand-drawing graphs, which can lead to errors, frustration, and lost opportunities for deeper reasoning. Using Tuva shifts the focus to sense-making. Students begin by examining the table to identify the least and greatest values, helping them determine the range of the data. This step supports their understanding of why a scale must match the quantities being represented. Students then interact directly with the graph by adjusting the scale in real time. As they drag the top of the graph up and down, they notice how the bars become too tall, too short, or just right. This dynamic manipulation makes the abstract idea of “scale” visible and concrete, allowing students to compare how different scales affect the clarity, accuracy, and readability of the graph. Tuva also reduces barriers for students with disabilities or fine motor challenges who may struggle with traditional graph construction. By removing the setup demands, every student can fully participate in the mathematical thinking: analyzing the data, evaluating multiple representations, and justifying which scale makes the graph easiest to read. Ultimately, the activity keeps the focus where it belongs—on interpreting data and making thoughtful choices about scale, not on drawing. Letting students explore the effects of different scales strengthens their conceptual understanding and supports more meaningful classroom discussion.
Before we start the next activity, let’s remember something important about bar graphs. When the numbers on the scale go up by more than 1 each time, we call it a scaled bar graph. These three bar graphs show the same data, but they look different because they use different scales. One counts by 1s, one counts by 2s, and one counts by 10s. When you make a scaled graph, you can skip count (like by 2s, 5s, or 10s). The scale you choose changes how the graph looks and how easy it is to read.
Topics and standards: Illustrative Math & Tuva, Grade 3