# Lesson 4

Día 1 de centros

## Warm-up: Conversación numérica: Usemos decenas para sumar (10 minutes)

### Narrative

The purpose of this Number Talk is to elicit strategies and understandings students have for making ten to find sums within 50. When students notice how they can make a ten when finding the value of each expression or when they use one sum to find the value of the next sum, they look for and make use of structure and express regularity in repeated reasoning (MP7, MP8).

### 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

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

### Student Facing

Encuentra mentalmente el valor de cada expresión.

• $$9 + 6$$
• $$29 + 6$$
• $$39 + 7$$
• $$39 + 9$$

### Activity Synthesis

• “¿Alguien usó el mismo método, pero lo explicaría de otra forma?” // “Did anyone have the same method but would explain it differently?”
• “¿Alguien pensó en el problema de otra forma?” // “Did anyone approach the problem in a different way?”

## Activity 1: Conozcamos “¿Qué tan cerca?: Suma para obtener 100” (20 minutes)

### Narrative

The purpose of this activity is for students to learn stage 3 of the How Close center. Each student picks seven cards and chooses four of them to create 2 two-digit numbers. Each student adds the numbers and the student whose sum is closest to 100 wins a point for the round.

### Required Materials

Materials to Gather

Materials to Copy

• How Close? Stage 3 Recording Sheet, Spanish

### Launch

• Groups of 2
• Give each group a set of number cards and recording sheets.
• “Vamos a aprender una nueva forma de jugar ‘¿Qué tan cerca?’. Juguemos una ronda juntos” // “We are going to learn a new way to play How Close? Let’s play one round together.”
• Demonstrate removing any card that shows the number 10.
• “Primero, cada uno toma 7 tarjetas” // “First we each take seven cards.”
• Display seven cards for you and seven for the class.
• “Después, cada uno escoge cuatro números para formar 2 números de dos dígitos. Queremos escoger números que, sumados, se acerquen lo más posible a 100 sin pasarse de 100” // “Then we each choose four numbers to make 2 two-digit numbers. We want to choose numbers that will have a sum as close to 100 as possible without going over.”
• Demonstrate making two-digit numbers and invite students to share what numbers they would make from the student set of cards.
• “Ahora, cada uno, suma sus números para que podamos ver quién tiene una suma más cercana a 100” // “Now we both add our numbers so we can see who has a sum closer to 100.”
• Demonstrate adding and comparing the numbers.
• “La persona con la suma más cercana a 100 obtiene un punto. Después, cada uno escoge cuatro tarjetas más para completar siete tarjetas y empezar la siguiente ronda. Gana la persona que obtenga más puntos” // “The person with the sum closer to 100 gets one point. Then you each choose four more cards so that you have seven cards to start your next round. The person who gets more points wins.”

### Activity

• 10 minutes: partner work time

### Activity Synthesis

• Display seven cards.
• “¿Qué números formarían para acercarse lo que más puedan a 100?” // “What numbers would you make to get as close as possible to 100?”

## Activity 2: Centros: Momento de escoger (20 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that focus on two-digit numbers.

Students choose from any stage of previously introduced centers.

• Target Numbers
• Five in a Row
• Get Your Numbers in Order

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from:
• Target Numbers, Stages 1–3
• Five in a Row, Stages 1–6
• Get Your Numbers in Order, Stage 1

### Launch

• Groups of 2
• “Ahora van a escoger centros de los que ya conocemos” // “Now you will choose from centers we have already learned.”
• Display the center choices in the student book.
• “Piensen qué les gustaría hacer primero” // “Think about what you would like to do first.”
• 30 seconds: quiet think time

### Activity

• Invite students to work at the center of their choice.
• 8 minutes: center work time
• “Escojan qué les gustaría hacer ahora” // “Choose what you would like to do next.”
• 8 minutes: center work time

### Student Facing

Escoge un centro.

Números objetivo

Cinco en línea

Ordena tus números

### Activity Synthesis

• “¿Qué practicaron y en qué mejoraron al trabajar en su centro?” // “What did you practice and get better at in your center?” (I worked on adding numbers by composing a ten.)

## Lesson Synthesis

### Lesson Synthesis

“¿Cómo les fue trabajando con su pareja en los centros? ¿Qué salió bien? ¿Qué podemos mejorar?” // “How did you and your partner work together during centers? What went well? What can we continue to work on?”