Lesson 17

This Number Talk encourages students to use their experiences counting coins and skip counting by 10 and 5 to add within 100. The understandings elicited here will be helpful in later lessons when students solve money problems with amounts including dollars and cents.

• Display one expression.
• “Hagan una señal cuando tengan una respuesta y puedan explicar cómo la obtuvieron” // “Give me a signal when you have an answer and can explain how you got it.”
• 1 minute: quiet think time

• Record answers and strategies.
• Keep expressions and work displayed.
• Repeat with each expression.

• “¿Cómo nos podrían ayudar estas expresiones a pensar en cómo resolver problemas sobre dinero?” // “How could these expressions help us think about solving money problems?” (It’s like adding quarters, dimes, and nickels.)

The purpose of this activity is for students to find coin combinations that have a value of 100 cents and make connections between coin collections that have the same value. They are invited to connect the value of nickels to dimes and relate their understanding of place value to represent 100 cents with dimes (MP7). In the next activity, students learn that 100 cents is the same as a dollar.

• Display the money poster where students can see it to check coin values.

• Groups of 2

• “Hoy vamos a seguir trabajando con dinero” // “Today, we will continue our work with money.”
• “Identifiquen las monedas que hay en cada grupo y cuenten para ver cuántas monedas hay en cada colección” // “For each set of coins, identify the coin and count to see how many coins are in the collection.”
• “Después, encuentren el valor total de las monedas usando un método que tenga sentido para ustedes” // “Then find the total value of the coins using a method that makes sense to you.”
• 8 minutes: independent work time
• “Comparen con un compañero” // “Compare with a partner.”
• 4 minutes: partner discussion

• “¿Cómo podrían usar lo que saben sobre los nickels para descifrar cuántos dimes necesitaban?” // “How could you use what you know about nickels to figure out how many dimes you needed?” (For every 2 nickels we needed 1 dime.)
• “¿Cuántos pennies necesitan para tener el mismo valor? Expliquen” // “How many pennies would you need in order to have the same value? Explain.” (100 because a penny is worth 1 cent, so you need 100 to make 100 cents.)
• “¿Qué observan acerca de cada colección de monedas? ¿Qué se preguntan?” // “What do you notice about each coin collection? What do you wonder?” (I notice it takes more nickels to have the same value than quarters or dimes. It only takes 4 quarters. It takes 10 dimes just like it takes 10 tens to make 100. Is 100 cents the same as a dollar? 

The purpose of this activity is for students to find combinations of coins with a value of 100 cents and understand that a dollar is the same as 100 cents. They add within 100 by grouping like coins, using a ten, or using counting on strategies. They find coin combinations that add up to 100 cents or 1 dollar and write the leftover amount as cents. This work builds on students’ understanding of a hundred.

•   Add a dollar bill to the money poster showing the front and back to display in the launch.

• Groups of 2
• Display the poster with the dollar added.

  

  

• “Acabamos de ver que hay diferentes maneras de usar monedas para formar 100 centavos. Un dólar también es lo mismo que 100 centavos” // “We just saw that there are many different ways to use coins to make 100 cents. One dollar is also the same as 100 cents.”
• “Si tengo un dólar y encuentro un quarter, ¿cuánto dinero tengo?” // “If I have a dollar and I found a quarter, how much money would I have?” (125 cents or \$1 and 25¢)
• 30 seconds: quiet think time
• Display a dollar and a quarter and write $1 and 25¢.

  

  

• “Cuando escriben cantidades de dólares, usan el símbolo \$. Usen el símbolo ¢ para la cantidad que no se puede agrupar para formar un dólar” // “When you write dollar amounts you use the \$ symbol. Use the ¢ symbol for the amount that cannot be grouped to make a dollar.”

• “Ahora, con un compañero, van a formar dólares y centavos” // “Now, you are going to work with a partner to make dollars and cents.”
• 10 minutes: partner work time
• Monitor for students who show Priya's money in different ways to share in the Lesson Synthesis.

If students show the value of Andre and Han's coins only in cents, consider asking:

• “¿Cómo encontraste el valor total de las monedas?” // “How did you find the total value of the coins?”
• “¿Cuántos dólares tiene _____? ¿Cuántos centavos sobran?” // “How many dollars does _______ have? How many leftover cents would he have?”
• “¿Cómo puedes decir cuánto dinero tiene _____ usando dólares y centavos?” // “How could you say how much money _______has using dollars and cents?”

• “Observé que cuando estaban creando una colección de monedas para Priya, había diferentes soluciones” // “I noticed that when you were creating a coin collection for Priya, there were different solutions.”
• “¿Cómo es posible que todos hayan representado la misma cantidad de dinero?” // “How is it possible that everyone represented the same amount of money?” (Different coins can show the same amount, but you need a different number of coins.)
• Invite students to share different combinations of coins they used to make $1.
• Share and record responses.