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Topic A Represent Data to Solve Problems
Topic A channels the excitement of students as they enter grade 2 by mathematizing getting-to-know-you activities, which often include student interest surveys. Lesson 1 uses these activities to show students that math is a part of the world around them. As students express personal preferences and organize responses on a graph, they come to see how a graph can be used to organize data that would otherwise be difficult to visualize.
As students transition to working with bar graphs, they represent data more abstractly by coloring spaces on a grid. Students use a scale to help them track data without always counting all. The scale is a bridge between the number path in kindergarten and grade 1 and the number line in grade 2. The scale also previews concepts about the ruler. For example, students learn that, on a bar graph, the space from the beginning of the bar to the first line represents a count of 1, just as they will learn that the space from 0 to 1 on the ruler is one length unit.
In the last two lessons of this topic, students apply their knowledge of bar graphs to solve put together, take apart, and compare problems. Students may solve by counting all, by counting on, or by using simple addition or subtraction. Students answer questions such as, How many more worms than bees are at the park? When solving comparison problems, students determine how many more or fewer by comparing number or length. Students may use one-to-one matching to solve. Alternatively, they may add or subtract to make the bars equal in length. The visual nature of a bar graph sets the stage for using tape diagrams as a representational tool to solve word problems later in the module.
Intentionally launching grade 2 with categorical data provides the opportunity throughout the year to use data contexts to give meaning to and support problem solving with addition and subtraction—the major work of grade 2.
