Counting Coins Again
Lesson 12 of 16
Objective: SWBAT find the value of different combinations of coins.
I begin today by writing 2N + 3D + 1Q on the board. I ask students how much money I have in all. (My students have been introduced to the notation of N=nickel, D=dime, Q=quarter, and P=penny in previous lessons.) I wait for students to write the answers in their math journals. Now I ask for a volunteer to tell us how much we have. I ask for a thumbs up for those who agree. I then ask if anyone has a different answer. I record each answer on the board.
If everyone does not agree we write out the amounts together and count them: 2N = 10cents, 3D = 30 cents and 1 Q = 25 cents. 10 + 30 = 40 and 40 + 25 = 65 so we have 65cents in all. Students are modeling with math as they write the amounts for the coins to solve the problem (MP4)
I repeat this process with several other examples. I do not use half dollars in this exercise.
When I feel that students are comfortable with the process I invite them to the rug to introduce a new game.
A New Game
I have small white boards (you could use paper and clip boards), markers and coins (pennies, nickels, dimes and quarters). On one of the boards I write P, N, D, Q down the side. Next I write an amount next to each letter. I tell students their numbers should be less than 9. I write 6 next to the P, 4 next to the N, 3 next to the D and 4 next to the Q. I tell students that they will play in threes. One person will write the amounts of coins on the white board. The other two will use the coins to figure out the total value of the money. The first person with the right answer gets a point. I tell students they can create a score card at the bottom of the board. This activity encourages students to create models for the math and then use them to solve the problem (MP4)
I choose 2 students to be my partners and ask them to use the coins to figure out how much money I have (the total value of the coins). I try to use the word value along with the term how much because I want them to become more comfortable with the term value.
I remind students that the writer also needs to know the value of the coins and if the group all has different answers they should count the coins together.
I demonstrate the game with a second round and then check for understanding with a thumbs up for all who feel comfortable with the rules of the game.
I divide students into groups of 3, hand them a white board, a marker and a cup of coins and allow them to move off to play the game.
During the game I circulate around and check in with each group to check for their understanding of the game, and of finding the value of the coins.
I ask students to clean up their materials and return to their seats. I have put 2 word problems on the board dealing with the value of money:
1. I have 3 dimes and 6 pennies. I want to buy an ice cream cone for 78 cents. How much more money do I need?
2. I have 3 quarters, 2 dimes, 3 nickels and 5 pennies in my wallet. I have a lemonade stand and I get 4 dimes, 2 quarters and 5 pennies from the sale of lemonade. What is the value of the money I have now?
I ask students to figure out the problems in their math journals. I give students time to complete the problems. I tell students who are done more quickly that they should write their own problem to share.
When everyone is done, we work together on the board to solve the problems. If we have time I allow students who wrote their own problems to read them to us and students solve them in their math journals.