Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.

a. Make tables of equivalent ratios relating quantities with whole-number measurements, find missing values in the tables, and plot the pairs of values on the coordinate plane. Use tables to compare ratios. [6-RP3a]

b. Solve unit rate problems including those involving unit pricing and constant speed. [6RP3b]
Example: If it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were the lawns being mowed?

c. Find a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent. [6-RP3c]

d. Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities. [6-RP3d]

Tape diagrams are defined in the Common Core Standards as
• Drawings that look like a segment of tape, used to illustrate number relationships. Also known as strip diagrams, bar models or graphs, fraction strips, or length models.

For more information, see this presentation by an Australian math specialist and an article about how tape diagrams are used in Japanese schools.

Success with Word Problems Using Singapore Math Model Drawing
Wonderful resource with lots of problems.

Double number line diagrams

North Carolina's Lessons for Learning
Bake Sale Brownies (p. 3) - 6.RP.3, 6.EE.9
• I can use knowledge of multiplication and division to scale recipes to make different numbers of servings.
• I can identify quantitative relationships between scaled recipes.
• I can represent relationships between quantities by plotting points on the coordinate grid.