# Introduction to Subtracting Money

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## Objective

SWBAT subtract money amounts under \$1.00

#### Big Idea

In this lesson, students develop strategies for subtracting money amounts under \$1.00

## Entrance Ticket

5 minutes

I start class by handing out an entrance ticket.  I allow students 2-3 minutes to work on the entrance ticket. This is a warm up for students.  We will use this entrance ticket during the introduction to new material.    (Students can do this entrance ticket on their paper or can work off the board in their math journals).

## Introduction to New Material

10 minutes

After students have finished their entrance ticket, I bring them back together and go over the entrance ticket by asking students to share their answers with a partner.

Turn and talk: How much money does Julie have? What strategy did you use to determine how much money Julie has?

After a 1 minute share, I ask two or three students to share out how much money Julie has AND how they determined the total.

Students should be able to use the strategies that we have worked on for the past few days to identify that Julie has 67¢ like grouping coins by denomination and skip counting or adding using column addition.   If students are struggling, I spend time modeling how to determine how much money Julie has and/or have a student model his or her strategy for the class.

Now, we are going to work on a problem of the day.  I want you to solve this problem of the day on the bottom or back of your entrance ticket.

I write the following problem of the day on the board:

Problem of the Day:  Julie goes to the store and buys some gum that costs \$.10.  How much money does Julie have now?

As students work, I circulate to determine common strategies—some students might simply cross out the dime and re-add the total. Others might add up the total and then subtract the dime.

After allowing students 1-3 minutes to work, I ask them to turn to a different thinking partner and share their answer and how they solved their problem:

Turn and Talk: Share with your neighbor how you solved this problem.

As students share,  I circulate to listen to student conversation and ask guiding questions like: how do you know your work is accurate?  How did you know to subtract?  Why did you set the problem up like that?

When finished, I bring everyone else back together and have two or three students share their strategies. I write these strategies on the board or on an anchor chart.

## Guided Practice

10 minutes

Now that we have worked on our problem of the day, we are going to practice making change and determining how much money we have left using our coin manipulatives.

In groups of two or three you will build a total using coins and then you will take some money away in order to find a total.  You can use the strategies we talked about during our problem of the day to help you determine how much money you have left.

I divide students into heterogeneous groups of two or three.  Each group should get one bag of mixed coins,  and one worksheet per students.  In groups, students:

1) Make a total using their coins (this a review from previous lessons)

2) Subtract the given amount from the total using the strategies discussed during the INM (crossing out or taking away the coins that were "spent", or  subtracting the amount spent from the total).

3) Students record findings on their worksheet.

As students work in groups or partners, I circulate and support students who are struggling.

## Independent Practice

10 minutes

After the guided practice, I divide students into heterogenous pairs. I chose to do this so that students have exposure to a variety of strategies.

We are going to work in pairs to solve a similar problem to our problem of the day. If you are struggling, remember the strategies that we talked about today.

As students work, I circulate to check in on students who were struggling and to identify which strategies are working well for students.

## Closing

5 minutes

Today we started learning how to subtract money.  Turn to your partner and share one strategy that you learned today.

After students have finished sharing, I ask one or two students to share a strategy that they used and why that strategy was useful for them.

Tomorrow, we will start making change with amounts greater than \$1.00.