Topic 4: Ratios
Students begin this topic by learning about ratios as multiplicative comparisons, contrasting them with additive comparisons. "More than" and "less than" are examples of additive comparisons, whereas "twice as many" and "one half as many" are examples of multiplicative comparisons. Students learn about quantitative relationships represented by ratios and the different ways to represent ratios. They are introduced to percent as a special ratio, namely an amount per 100. Students use their initial understandings of ratio to model and determine equivalent ratios. To generate and display equivalent ratios in real-world and mathematical problems, they use tape diagrams, double number lines, scaling up and down, tables, and graphs.
