Lesson Plan

Identify whether two quantities vary directly, inversely, or neither (from a table, from wording, or from a context in which the word "varies" does not appear), and use the relationship and one known pair to find an unknown value

Find the constant of variation from a table (every ratio y/x constant, or every product xy constant) or from one known pair, state its units, and write y = kx or y = k/x

Apply the scale-factor property (the same factor under direct variation, the reciprocal factor under inverse variation), converting a percent-phrased change into a growth factor first

Distinguish direct variation from a linear relationship that is neither, using the doubling test and the origin test

"Questions will require students to solve problems by using a proportional relationship between quantities, calculating or using a ratio or rate, and/or using units, derived units, and unit conversion." "Understand and use the fact that when two quantities are in a proportional relationship, if one changes by a scale factor, then the other also changes by the same scale factor." "Apply proportional relationships, ratios, and rates in a wide variety of contexts. Examples include, but are not limited to, scale drawings and problems in the natural and social sciences." → sat-psda-ratio-prop "Solve problems involving derived units, including those that arise from products (e.g., kilowatt-hours) and quotients (e.g., population per square kilometer)." → sat-psda-ratio-unit "Solve problems involving: » a one-step unit conversion. » a multistep or multidimensional unit conversion." → sat-psda-ratio-unit