Scaling Recipes with Ratios: A Super Cake Adventure!

Mathematics Grades 7th Grade 4:51 Video
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Lesson Description

Learn how to use ratios to adjust recipes for different serving sizes, ensuring your cake tastes delicious no matter how many guests you have!

Video Resource

Ratios for recipes

Khan Academy

Duration: 4:51
Watch on YouTube

Key Concepts

  • Ratio
  • Proportion
  • Scaling Recipes
  • Equivalent Ratios

Learning Objectives

  • Students will be able to define a ratio and give examples.
  • Students will be able to calculate the new quantity of an ingredient when a recipe is scaled.
  • Students will be able to explain how ratios maintain the flavor profile of a recipe when scaled.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students if they've ever helped cook or bake. Have they ever needed to adjust a recipe? Briefly discuss the challenges and importance of maintaining the correct proportions.
  • Video Viewing (7 mins)
    Play the Khan Academy video 'Ratios for Recipes.' Instruct students to take notes on the key concepts presented, particularly the definition of a ratio and how it applies to scaling recipes.
  • Guided Practice (10 mins)
    Work through a sample recipe scaling problem together as a class. For example, provide a recipe for cookies that serves 24 and ask students to calculate the ingredient amounts needed to serve 12, 6, and 48 people. Emphasize setting up the problem as a proportion and solving for the unknown variable.
  • Independent Practice (10 mins)
    Provide students with a worksheet containing several recipe scaling problems. Have them work individually or in pairs to solve the problems. Circulate to provide assistance and answer questions.
  • Wrap-up and Discussion (3 mins)
    Reiterate the importance of ratios in maintaining the quality of a recipe. Briefly discuss other real-world applications of ratios and proportions (e.g., map scales, unit conversions).

Interactive Exercises

  • Recipe Remix
    Divide students into small groups and provide each group with a different recipe. Have them choose a new serving size and recalculate all the ingredient amounts. Each group then presents their scaled recipe to the class.

Discussion Questions

  • Why is it important to maintain the correct ratios when scaling a recipe?
  • Can you think of other situations in everyday life where ratios and proportions are important?
  • What are some strategies for solving ratio problems?

Skills Developed

  • Problem-solving
  • Proportional Reasoning
  • Critical Thinking
  • Ratio Calculations

Multiple Choice Questions

Question 1:

What is a ratio?

Correct Answer: A comparison of two quantities.

Question 2:

If a recipe calls for 2 cups of flour and you want to double the recipe, how much flour do you need?

Correct Answer: 4 cups

Question 3:

A recipe for 10 cookies calls for 1 egg. How many eggs are needed for 30 cookies?

Correct Answer: 3

Question 4:

What happens if you don't maintain the correct ratios when scaling a recipe?

Correct Answer: The recipe might not turn out correctly.

Question 5:

Which of the following is an example of a ratio?

Correct Answer: There are 3 cats and 2 dogs.

Question 6:

A recipe uses 1 cup of sugar for every 4 cups of flour. What is the ratio of sugar to flour?

Correct Answer: 1:4

Question 7:

If you want to halve a recipe, what operation do you perform on the ingredients?

Correct Answer: Division by 2

Question 8:

A cake recipe needs 2 eggs and 1 cup of milk. If you have 6 eggs, how many cups of milk do you need to keep the ratio the same?

Correct Answer: 3 cups

Question 9:

What does it mean to 'scale' a recipe?

Correct Answer: To change the serving size

Question 10:

What is another word for constant of proportionality?

Correct Answer: Unit Rate

Fill in the Blank Questions

Question 1:

A ______ is a comparison of two quantities.

Correct Answer: ratio

Question 2:

If a recipe calls for 3 teaspoons of salt and you triple the recipe, you will need ______ teaspoons of salt.

Correct Answer: 9

Question 3:

When scaling a recipe, the ______ between ingredients should remain the same.

Correct Answer: ratios

Question 4:

If a recipe for 5 servings requires 1 cup of sugar, then a recipe for 15 servings will require ______ cups of sugar.

Correct Answer: 3

Question 5:

Changing a recipe to feed more or less people is called _____ the recipe.

Correct Answer: scaling

Question 6:

A ratio can be written as a fraction, using a colon, or with the word _____

Correct Answer: to

Question 7:

The _____ of eggs to flour in a recipe must stay the same when you scale the recipe.

Correct Answer: ratio

Question 8:

If you need to increase all the ingredients in a recipe, you must do the same operation to _____ of them.

Correct Answer: all

Question 9:

Ratios can be simplified by _____ both sides by the same amount

Correct Answer: dividing

Question 10:

Scaling a recipe is a real-world example of _____ reasoning.

Correct Answer: proportional

Educational Standards

7.A.2.3:Use proportional reasoning to solve problems involving ratios. 7.A.2.2:Solve multi-step problems with proportional relationships (e.g., distance-time, percent increase or decrease, discounts, tips, unit pricing, mixtures and concentrations, similar figures, other mathematical situations). 7.N.1.2:Recognize and generate equivalent representations of rational numbers, including equivalent fractions.

Teaching Materials

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