Adding money amounts (Part III)

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Objective

SWBAT add money amounts to create totals greater than $1.00

Big Idea

In this lesson, students build on their knowledge of coins and place value to add money amounts to create totals greater than one dollar.

Introduction to New Material

15 minutes

I start class by putting one hundred pennies underneath my document camera.  

We are going to count these pennies and see how many I have. How can we group these pennies to easily count them?  

Students might suggest counting in 5s or 10s--have students count the coins in groups of 10 if possible. 

I choose a student to lead the class in counting the pennies by grouping them into tens.  When the class gets to 100, I ask "how much money do I have?"  Some students might suggest that we have 100 cents.  Others might remember that 100 cents equals one dollar.  

Then, I add another penny (or two).  I ask the class, "How much money do I have now?"  Some students might still suggest that I have 101 cents and others might understand this is equivalent to $1.01.

How many pennies are in one dollar?

When I have 100 pennies, I have a dollar.  When I have 101 pennies, I have one dollar and one cent, which we write like this ($1.01).  Our decimal point separates the dollar amount from the cent amount. 

Now, I have a problem of the day for you:

Last night, I went to the store and I saw some treats I wanted to buy.  I saw a muffin for $.33, a donut for $.68 and a cupcake for $.75.  How much money do I need?

I divide the class into heterogenous groups of three or four and give them a bag of coin manipulatives.

Use the coins in front of you to show me how much money I need to by the muffin, the donut, and the cupcake. 

As students work, I circulate and check for understanding, asking students to explain how much money I need.

When finished, I ask two or three students to share how much money I need and how they figured it out.

I continue to push students to understand that 100 cents are in one dollar: I see that you have 143 cents.  How else can we write this amount?

When finished discussing using the coin manipulatives, I hand students white boards and explain that we're going to do the same problem using column addition. I remind students to line up the decimal points and then allow them to solve the problem on their own. 

Afterwards, I have at least one student model how he/she solved the problem, modeling how they dropped the decimal point and created a dollar. 

If time permits, I have students do another problem on their white boards before releasing students to the guided practice. 

Guided Practice

15 minutes

Yesterday, we had a school store where you picked items and figured out how much money you needed!  Today, we are going to have school store again but this time the prices are higher and you will need to carry to create a dollar.

School store can be set up in two ways:

1) Set out various items and label them with prices.  Students can choose the items they want and add up the total on the attached worksheet.

2) Set up a "virtual" school store by posting items on the board or handing students the attached price sheet.  Students can choose the items they want and add up the total  on the attached worksheet.

As students work, I circulate to check for understanding and support students who are struggling, especially those who are struggling to understand how to create a dollar when they carry. 

Materials:

School Store Recording Sheet

School Store Price List

 

Independent Practice

10 minutes

During the independent practice, students will work alone or in pairs to solve two problems where they have to create a total greater than $1.00.

As students work, I circulate to check for understanding, help students who are struggling and ask guiding questions:

 (1) What strategy did you use?

 (2) What did you do to make sure your work was accurate?

 (3) What is the difference between _____ cents and $__. ____?  (Students should be able to explain that they are the same thing but we represent money amounts using dollars and cents).

Exit Ticket

10 minutes

I give my students an exit ticket to assess their mastery of adding up money beyond $1.00.  As students work, I circulate to check for understanding and see what strategies students are using.

I go over the exit ticket with students so that they can receive immediate feedback on their work.