Exploring Rate In The Context Of Shopping

Exploring Rate In The Context Of Shopping

Breaking Eggs

Opening

Breaking Eggs

Watch the video.

  • What information do you know about this situation?

VIDEO: Broken Eggs

Math Mission

Opening

Calculate the unit price of an item and use this rate to find the cost of any number of items.

The Price of 9 Eggs

Work Time

The Price of 9 Eggs

Carlos wants to buy 9 eggs.

  • How much will the 9 eggs cost?
  • Include in your solution:
    • The quantities involved in the problem
    • A diagram, table, double number line, or other representation that shows why your solution makes sense
    • An equation, your work, and the solution
    • A complete sentence that answers the question
  • Remember that there are often multiple ways to solve a math problem. If you have time, try solving this in more than one way.

Hint:

  • Do you think the price will be greater or less than the price of 12 eggs?
  • How much would 1 egg cost?
  • Does your answer make sense?

Prepare a Presentation

Work Time

Prepare a Presentation

  • Explain how you determined the cost of 9 eggs.
  • Use your work to support your explanation.

 

Challenge Problem

  • Which is a better buy: $1.79 for 32 ounces of a sports drink, or $0.83 for 12 ounces of the same sports drink?
  • Explain your thinking.

Make Connections

Performance Task

Ways of Thinking: Make Connections

Take notes about your classmates’ approaches to solving the problem.

  • Determine an approach you will use to solve a different problem involving unit price.

Hint:

As your classmates present, ask questions such as:

  • What are the quantities in this situation?
  • What equation did you use?
  • Where do you see the price of 1 egg in your equation?
  • What operation did you use to find the unit price? Explain your thinking.
  • Does your answer make sense? Why?
  • If you know the unit price, how do you find the price for any amount of eggs?
  • You used an equation and another student used a table to find the cost of 9 eggs. Can you compare the two representations?

Find the Unit Price

Work Time

Find the Unit Price

Emma buys 3 pounds of apples for $7.50.

  • What is the unit price of the apples?

Hint:

  • What are the two quantities in this problem?
  • How can you find the cost of 1 pound of apples?
  • What operations would you use?
  • Does your answer make sense?

Find the Cost

Work Time

Find the Cost

Emma changes her mind. Instead of buying 3 pounds of apples for $7.50, she buys 7 pounds.

  • How much money will she pay for the apples?

Hint:

Once you know what 1 pound of apples costs, how can you find the cost of 7 pounds?

Comparing Prices

Work Time

Comparing Prices

Carlos bought a box of cereal. The box contained 16 ounces of cereal and cost him $4.00.

Emma bought a box of a similar cereal. The box contained 24 ounces of cereal and cost her $6.00.

  • Who got the better deal? Explain how you know.

Hint:

  • What are the two quantities in this problem?
  • How can you find the cost of 1 ounce?
  • What operations should you use?
  • Does your answer make sense?

Understanding Unit Price

Formative Assessment

Summary of the Math: Understanding Unit Price

Read and Discuss

  • The unit price is a rate that tells you the price of 1 unit of something—for example, the price of 1 pound of cheese, 1 quart of milk, 1 box of paper clips, 1 package of cereal, and so on.
  • The unit price, or rate, can be found by dividing the price in dollars by the number of units.
  • The unit price can be used to find the price of any quantity by multiplying the unit price by the quantity.

Hint:

Can you:

  • Explain what unit price means and how to find it?
  • Include the term rate ?
  • Explain how to find the total price of an item by using its unit price?

Reflect On Your Work

Work Time

Reflection

Write a reflection about the ideas discussed in class today. Use the sentence starter below if you find it to be helpful.

As I worked on unit price problems, I found that a useful strategy is …