Module 2 • Topic 1 • Lesson 2

Comparing Ratios and Rates to Solve Problems

Mix lemonade, stir hot chocolate, sort punch, and pick a penalty-shot taker. Predict first, then test your idea and watch what happens.

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Today you will

  • Compare quantities with numbers and without numbers.
  • Define and use rates to solve problems.
  • Compare and order part-to-part and part-to-whole ratios and rates shown with words, pictures, and numbers.
1. Predict2. Test it3. Check4. Stamp the learning

Your writing stays on this device. Please do not type your name or other personal information. Labs unlock after you make a prediction and explain it.

Essential question

You know how to write a ratio as a comparison of two quantities.

How can you compare two ratios to make decisions in real-world situations?

Getting Started: Lemony-er Lemonade

ACTIVITY2.1

Qualitative Comparisons

In this activity you will compare two quantities without measuring or counting quantities. When you reason like this, it is called qualitative reasoning.

Language help

Think-Pair-Share in threes. There are a lot of words in these situations. Work in groups of three. Each person takes one part of Question 1 (1a, 1b, or 1c), talks it through, and then teaches it to the other two. Use Listen to hear any scenario read aloud.

teaspoon
A very small spoon for measuring. Lemon mix is measured in teaspoons here.
fluid ounce
A small amount of liquid. Two fluid ounces is about a small shot glass.
tablespoon
A bigger measuring spoon. It is written with a capital T.
lap
One trip all the way around a race track.
pitcher
A large container with a handle for pouring drinks.
ACTIVITY2.2

Comparing Comparisons

A rate is a comparison by division between two quantities that have different units. The 6th-grade students are making hot chocolate to sell at the Winter Carnival. Each homeroom (HR) suggested a different recipe.

The "T" in each recipe stands for Tablespoon!
1 cup holds 16 tablespoons.
Ask yourself… What units can you use to compare the amount of milk to the amount of cocoa powder?
Language help

Some people may not know the unit tablespoon. It is a measuring spoon, shown next to a cup above. The Word helper in the thinking tools (below) explains the other math words too.

ACTIVITY2.3

Ordering Part-to-Part and Part-to-Whole Rates

Suppose your class is in charge of providing punch at the upcoming open house. The Parent-Teacher Association bought lemon-lime soda and pineapple juice to combine for the punch, but they did not tell your class how much of each to use. Your classmates submitted suggestions for how to make the tastiest punch.

Sort the Punch Rate Cards from the least lemon-lime concentration to the most lemon-lime concentration. When you think more than one card describes the same ratio of lemon-lime soda and pineapple juice, group those cards together.

lemon-lime soda (gray) pineapple juice (white)

The shading, or lack of shading, of each cup shows the type of concentration. Not every ratio is shown in every form.

Talk the Talk: Put Me In, Coach

A soccer team has been awarded a penalty shot at the end of a tie game. If they make the penalty shot, they will win the league championship. The coach is considering three players to take the penalty. Jasmine has taken 4 penalty shots this season and has made 3 of them. Luna has taken 6 penalty shots and made 4. Kayla has taken 3 penalty shots and made 2.

Ask yourself… How can you organize and record your mathematical ideas?

Wrap-up

Essential question

How can you compare two ratios to make decisions in real-world situations?

Your first thoughts from the start of the lesson:

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