In previous lessons students have calculated and worked with rates per 1. The purpose of this lesson is to introduce the two unit rates, \(\frac ab\) and \(\frac ba\), associated with a ratio \(a:b\). Each unit rate tells us how many of one quantity in the ratio there is per unit of the other quantity. An important goal is to give students the opportunity to see that both unit rates describe the same situation, but that one or the other might be preferable for answering a given question about the situation. Another goal is for students to recognize that they can just divide one number in a ratio by another to find a unit rate, rather than using a table or another representation as an intermediate step. The development of such fluency begins in this section and continues over time. In the Cooking Oatmeal activity, students have explicit opportunities to justify their reasoning and critique the reasoning of others (MP3).
Lesson overview
 6.1 Warmup: Something per Something (5 minutes)
 6.2 Activity: Cooking Oatmeal (15 minutes)

6.3 Activity: Cheesecake, Milk, and Raffle Tickets (20 minutes)
 Includes "Are you Ready for More?" extension problem
 Lesson Synthesis
 6.4 Cooldown: Buying Grapes by the Pound (5 minutes)
Learning goals:
 Calculate and interpret the two unit rates associated with a ratio, i.e., \(\frac ab\) and \(\frac ba\) for the ratio \(a:b\).
 Choose which unit rate to use to solve a given problem and explain the choice (orally and in writing).
 Comprehend the term “unit rate” (in spoken and written language) refers to a rate per 1.
Learning goals (student facing):
 Let’s explore unit rates.
Learning targets (student facing):
 I can choose which unit rate to use based on how I plan to solve the problem.
 When I have a ratio, I can calculate its two unit rates and explain what each of them means in the situation.
Glossary:
 unit rate  A unit rate is a rate per 1. For example, 12 people share 2 pies equally. One unit rate is 6 people per pie, because \(12 \div 2 = 6\). The other unit rate is \(\frac16\) of a pie per person, because \(2 \div 12 = \frac16\).
 Access the complete Grade 6 glossary.
Standards:
 This lesson builds towards the standard: CCSS.6.RP.A.2MS.6.RP.2
IM 6–8 Math was originally developed by Open Up Resources and authored by Illustrative Mathematics, and is copyright 20172019 by Open Up Resources. It is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). OUR's 6–8 Math Curriculum is available at https://openupresources.org/mathcurriculum/.
Adaptations and updates to IM 6–8 Math are copyright 2019 by Illustrative Mathematics, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
Adaptations to add additional English language learner supports are copyright 2019 by Open Up Resources, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
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