Ratios

Lesson 1 Student Outcomes

• Students understand that a ratio is an ordered pair of non-negative numbers, which are not both zero. Students understand that a ratio is often used instead of describing the first number as a multiple of the second.
• Students use the precise language and notation of ratios (3:2, 3 to 2). Students understand that the order of the pair of numbers in a ratio matters and that the description of the ratio relationship determines the correct order of the numbers. Students conceive of real-world contextual situations to match a given ratio.
Lesson 1 Summary

• A ratio is an ordered pair of non-negative numbers, which are not both zero. The ratio is written or to to indicate the order of the numbers. The number is first, and the number is second.
• The order of the numbers is important to the meaning of the ratio. Switching the numbers changes the relationship. The description of the ratio relationship tells us the correct order for the numbers in the ratio.
Lesson 1 and Lesson 2

1. Write a ratio for the following description: For every 3 cups of flour in a chocolate chip cookie recipe, 1 cup of sugar is used.

2. Give two different ratios with a description of the ratio relationship using the following information: There are 16 boys in the chorus. There are 24 girls in the chorus.