In Ratios: Grade 6 Workbook , we concentrate on the concept of ratio and various applications involving ratios and rates. The workbook starts out with the basic concepts of ratio, rate, and unit rate. The lesson Equivalent Rates allows students to solve a variety of word problems involving ratios and rates. We also connect the concept of rates (specifically, tables of equivalent rates) with ordered pairs, use equations (such as y = 3 x ) to describe these tables, and plot the ordered pairs in the coordinate plane. Next, we study various kinds of word problems involving ratios and use a bar model to solve these problems in two separate lessons. These lessons tie ratios in with the use of bar models as a tool for problem solving. Then, students encounter the concept of aspect ratio, which is simply the ratio of a rectangle’s width to its height, and solve a variety of problems involving aspect ratio. Lastly, students learn how rates can be used to convert measurement units. It does not mean that students should “change over” and forget methods they have already learned for converting measurement units—it is simply a different method for doing the conversions. Some students may choose one method over another; some may be able to master all of the methods. Most will probably choose one method they prefer for doing these conversions.