Tens and Ones, Dimes and Pennies
Lesson 10 of 14
Objective: SWBAT count dimes and pennies together. SWBAT explain base 10 models that would match dime and penny models.
Objective & Hook
Place value is a huge emphasis within the lower grades in the CCSS. Students in first grade learn the concept of ten and then apply it in a variety of ways throughout the year. 1.NBT.2 asks students to understand that the two digits of a two-digit number represent amounts of tens and ones. This lesson is an example of how to connect base ten to something more abstract: Coin values. In this lesson, students will use their understanding of base ten to create coin amounts using dimes and pennies. They connect to 1NBT2 as they see that the corresponding number of tens and ones also tells them the number of dimes and pennies. This lesson is a great extension for first grade material, and also is aligned to 2.MD.C8, which asks students to solve word problems using money.
Review Past Learning:
We have worked on base ten models all year-thinking about how 10 is our best friend and we can use 10 to help us solve problems. Today we are going to think about how our concept of 10 can help us when we use coins.
Connect to the real world:
Great mathematicians are always making connections. They make connections between things they already know and new things they are learning. Today you will get to make connections between 2 important things you have learned-money and base 10.
Your thinking job today is: How are dimes and pennies similar to tens and ones? How can that help us count?
Present problem: I REALLY want to buy a new ink pad for the stamping center but I don’t know how to pay for it. It costs 21 cents.
- Can I use just dimes to create this amount? Why not?
- We will test using just dimes to see if it works!
Partner talk: How could I make 21 cents then?
- More than likely, a student will suggest using a penny. I'll have this student share out their thinking to explain why we need a penny.
Present 2 dimes and 1 penny: I'll model labeling each coin with a D or a P to help me remember which coin it is. I'll also draw a line between the dimes and pennies. This line helps students remember to switch how they count. It is a small visual scaffold that goes a long way!
Today our thinking job was to see how dimes and pennies are like our base ten models. How would we show 21 using base ten blocks?
- Where are the 2 tens in our coins? Where is the one?
- If I want to make 21 with tens and ones, I use 2 tens and 1 one. How do I do it if I make it with coins? 2 dimes and 1 penny.
This discussion is aligned to MP8, as it asks students to consider the connection between base ten and coins, and then prepares them to use this reasoning in forthcoming problems.
Present new task: This time I want to buy a candy bar and it is 32 cents.
- Students will draw the coins on whiteboards and model how to count them. I use whiteboards here because I can see how everyone is solving quickly, and I can address any misconceptions in the moment either whole group or individually.
- Focus Question: How did you make the amount? How would we make it out of tens and ones?
See attached 32 cents chart for the models we made.
Present 2 more similar tasks, following the same routine:
I want to buy a sticker that costs 42 cents. How could I pay for it in dimes and pennies?
I want to buy a cold drink that costs 63 cents. How could I pay for it in dimes and pennies?
Present New Task: Now I am going to show you the coins I have in my pocket. I want you to draw them and figure out how much money I have.
- I'll show groups of coins and have students record them and show how to count them on their whiteboards.
- Focus Question: How can you use what you know about base ten models to help you count dimes and pennies?
Group A: Intervention
These students will receive an intervention coin counting sheet. This worksheet has students practice counting a group of dimes and then has them count that same group of dimes with pennies also.
Group B: Right on Track
Students solve word problems where they show how to use dimes and pennies to create a given amount.
Group A and B work can be found here: Dime Penny Mix Groups A_C.pdf
Group C: Extension:Dime Penny Mix Groups C.pdf
Students solve word problems where they add groups of coins together. In this work, students have to apply their understanding of base 10 and coin values to show how to add more dimes to a given group of coins.
Watch the attached video (Group C Number Sentence Discussion) to see how I discussed with one table what number sentence matches the Group C story. Some students will write 4+2+1=61 because they used 4 dimes, 2 dimes and 1 penny. See how I handle this misconception!