Unit 7: Ratios, Percentages, and Proportional Reasoning

Day 4 of 30

Understand part-to-part ratios

K-2Mathematics

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Learning Objective

I can understand part-to-part ratios.

Today's Lesson

Today we will learn how to understand part-to-part ratios. Math helps us solve problems and understand the world around us.

A ratio compares two quantities. For example, if there are 3 boys and 5 girls in a group, the ratio of boys to girls is 3:5 (read "3 to 5"). Ratios can also be written as fractions (3/5) or with the word "to" (3 to 5). Ratios help us compare amounts and understand relationships between numbers in recipes, maps, and many real-world situations.

Let's break this down step by step so it's easy to understand. Follow along with the examples, and don't worry if it takes some practice to get the hang of it!

Remember: Making mistakes is part of learning. If something is tricky, try again, look at the examples, or ask for help.

Key Terms
Problem

A question we need to solve

Solution

The answer to a problem

Activities
Instructions
1. Use objects or pictures to explore understand part-to-part ratios. 2. Try the examples together. 3. Solve practice problems. 4. Check your work.
Materials Needed
  • Counters or objects
  • Pencil
  • Practice sheet
Practice Problems
1

The ratio of boys to girls is 3:5. If there are 6 boys, how many girls are there?

Hint: Set up a proportion: 3/5 = 6/x
2

Express the ratio 6:9 in simplest form.

Hint: Divide both numbers by their GCF.
3

If 4 apples cost $2, how much do 10 apples cost?

Hint: Set up a proportion or find unit price.

Teaching Tip

For younger learners: Use concrete objects and hands-on activities when teaching understand part-to-part ratios. Keep sessions short (10-15 minutes) and incorporate movement or songs when possible.

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