# Lesson 17

Formemos un dólar

## Warm-up: Conversación numérica: Sumemos 25 (10 minutes)

### Narrative

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.

### Launch

• 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

### Activity

• Keep expressions and work displayed.
• Repeat with each expression.

### Student Facing

Encuentra mentalmente el valor de cada expresión.

• $$25 + 10 + 10 + 5$$
• $$25 + 25$$
• $$25 + 25 + 25$$
• $$25 + 25 + 25 + 25$$

### Activity Synthesis

• “¿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.)

## Activity 1: Muchos, muchos centavos (15 minutes)

### Narrative

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.

MLR8 Discussion Supports. Synthesis: Some students may benefit from the opportunity to rehearse what they will say with a partner before they share with the whole class.

### Required Preparation

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

• Groups of 2

### Activity

• “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

### Student Facing

1. Colección A de monedas

Marca el nombre de las monedas
de esta colección.

quarters

dimes

nickels

pennies

¿Cuántas monedas hay? __________

¿Cuál es el valor total en centavos?
Muestra cómo pensaste.

2. Colección B de monedas

Marca el nombre de las monedas
de esta colección.

quarters

dimes

nickels

pennies

¿Cuántas monedas hay? __________

¿Cuál es el valor total en centavos?
Muestra cómo pensaste.

3. Colección C de monedas

Haz una colección que tenga el mismo valor que la colección A usando solo dimes.

Pega o dibuja aquí las monedas.

¿Cuántas monedas hay?__________

¿Cuál es el valor total en centavos?
Muestra cómo pensaste.

### Activity Synthesis

• “¿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?

## Activity 2: El valor de un dólar (20 minutes)

### Narrative

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.

Engagement: Develop Effort and Persistence. Chunk the tasks by question and check in with students to provide feedback and encouragement after each question. Look for the students to be using a strategy and ask them to verbalize their solution to ensure they are on the right track.
Supports accessibility for: Language; Organization

### Required Preparation

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

### 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.”

### Activity

• “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.

### Student Facing

1. Andre desocupó sus bolsillos y encontró estas monedas.

¿Cuánto dinero tiene? Muestra cómo pensaste.

2. Han desocupó sus bolsillos y encontró estas monedas.

¿Cuánto dinero tiene? Muestra cómo pensaste.

3. Priya tiene en su bolsillo $1 y 18¢. 1. Si Priya solo tiene monedas en su bolsillo, ¿qué monedas podría tener? Representa las monedas de Priya: 2. Si Priya tenía 1 billete de dólar y algunas monedas, ¿qué monedas podría tener? Representa el dinero de Priya: ### Student Response Teachers with a valid work email address can click here to register or sign in for free access to Student Response. ### Advancing Student Thinking 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?” ### Activity Synthesis • “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.

## Lesson Synthesis

### Lesson Synthesis

“Hoy aprendimos que un dólar tiene el mismo valor que 100 centavos. Contamos valores que eran más de 100 centavos. Describimos estas cantidades como 1 dólar y unos centavos que sobran” // “Today we learned that a dollar has the same value as 100 cents. We counted values that were more than 100 cents. We described these amounts as 1 dollar with cents left over.”

Display students’ representations for Priya’s money in coins and as a dollar and coins.

“¿Se les ocurren diferentes formas de representar el mismo valor con más monedas o con menos monedas?” // “Can you think of different ways to represent the same value with more coins or fewer coins?”