Shopping Shuffle

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Students will identify unit rates and make decisions using them.

Big Idea

The big idea of this lesson is for students to recognize a unit rate and to apply the knowledge of a unit rate to solve problems.


10 minutes

As students enter the room, I will guide them to respond to the prompt on the board: “I’m going to buy popcorn for the class. Kroger has boxes with 3 bags of microwave popcorn on sale for $1.59 and Meijer has boxes with 5 bags of microwave popcorn on sale for $2.09, which store has the better buy? Explain your choice.” I want students to use this opportunity to justify their reasoning. While I want them to move toward the idea of unit rate, if the justification does not involve mathematics, I can use this to guide their thinking. This question, along with the discussion, will help me determine if students grasp the concept of finding unit rates. If there is prior knowledge, this will help activate it. If students do not have the background knowledge to support answering the question, that will be evident as we talk about the question.


30 minutes

After the discussion about the Problem of the Day, students will be placed into groups of three using the Random Group Generator on SMART board. Students will be randomly grouped to allow for a new interaction and discussion group. I believe that students benefit from having rich discussions with each other. These discussions don’t always have to be with a scripted group. Students who always sit next to each other or always chose each other in partner or group situations can become complacent. With the randomly generated group students may hear fresh ideas or a new way of approaching a problem.

Each student group will receive a card with a chart of prices for an item. The goal for the group is to complete the table to determine the cost for different amounts of the item. One unit of the item is included on each card. The goal is to get students familiar with finding the unit rate for the items. Students will also be given a sheet to record the values found to complete the table. Since the groups may not receive the item cards in a particular order, there is a place on the worksheet to indicate which card they are working on. After a given amount of time, 3 minutes, students will pass the card to the next group to solve. This process will continue until each group has seen the cards for Stores A-P.

To present group findings, each group will be assigned an item. As I walk around, listening to the groups work together to complete the charts, I can make decisions about whether to assign each group a chart to present or if I should let them choose an item. If any particular items cause confusion or challenge, I may need to choose a group to present that item. If no group successfully completes a chart, I can take the approach of using that chart as an opportunity for intervention with the whole class.  

As each group prepares to discuss their findings with the group, I will put the following questions on the board:

Which store offered the best rate for each item?

How did you determine that was the best rate?

Which store offered the most expensive rate?

What could a store change to make their rate more competitive?

What did you consider when deciding the best rate (package, size)?

Describe/talk about how you found the cost for one item.

Did your group run into any challenges completing your table? What did you do to work through it and complete the table?

If the presentations and discussion indicate there is misunderstanding about finding unit rates, additional problems and situations can be presented to the whole class.  If there are any tables that none of the groups could complete, I will use that table as a starting point for intervention. If there are students who have mastered this concept, I can ask them to either generate additional tables or to support individual students. We can also use tables that are based on price per pound or other units.


5 minutes

Describe the steps to find the unit rate of an item. How is knowing the unit rate for an item helpful?

I want students to share with me what they know about unit rate. Do they see the benefit of identifying a unit rate, especially as it applies to relelvant problems? If not, we need to have discussion on finding unit rate and the applications of unit rate.