Lesson Objective: Practice relating unlike units on double lines and reinforce understanding of intervals on the number lines.

Students practice maintaining proportional relationships and finding missing values using double number lines. The parallel number lines will reappear in Unit 2 as a pair of perpendicular number lines, and the relationships shown here as a vertical match will become a bivariate data point.

Students engage in Mathematical Practices 1 and 6 in this lesson. They use a double number line model complex scenarios in the In-class Practice, but are not prompted about which operations to use to solve them. They must therefore make sense of the problems (MP1) and attend to precision (MP6), maintaining the correspondence between quantities even as they convert between units of measure.

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