This lesson introduces students to the idea of unit price. Students use the word “per” to refer to the cost of 1 apple, 1 pound, 1 bottle, 1 ounce, and so on, as in “\$6 per pound” or “\$1.50 per avocado.” They also learn that the phrase “at this rate” is used to indicate that the ratios of price to quantity are equivalent. (For example, “Pizza costs \$1.25 per slice. At this rate, how much do 6 slices cost?”) They find unit prices in different situations and notice that unit prices are useful for computing prices for other amounts (MP7).

Students choose whether to draw double number lines or other representations to support their reasoning. They continue to use precision in stating the units that go with the numbers in a ratio in both verbal statements and diagrams (MP6).

Note that students are not expected to use or understand the term “unit rate” in this lesson.