# Lesson 16

Encontremos el valor de expresiones

## Warm-up: ¿Qué sabes sobre $3+2$? (10 minutes)

### Narrative

The purpose of this What Do You Know About ____? is to invite students to share what they know and how they can represent the expression $$3 + 2$$.

### Launch

• Display the expression.
• “¿Qué saben sobre $$3 + 2$$?” // “What do you know about $$3 + 2$$?”
• 1 minute: quiet think time

### Activity

• Record responses.
• “¿Cómo podemos mostrar $$3 + 2$$?” // “How could we show $$3 + 2$$?”

### Student Facing

¿Qué sabes sobre $$3 + 2$$?

### Activity Synthesis

• “¿3 y 2 es cuánto? ¿Cómo lo saben?” // “3 and 2 is how many? How do you know?”

## Activity 1: Conozcamos “Lanza y suma: Expresiones de suma” (10 minutes)

### Narrative

The purpose of this activity is for students to learn stage 2 of the Roll and Add center. Students roll to find 2 numbers, fill in an expression, and find the value of the expression. The purpose of the activity synthesis is to highlight different representations students used to find the value of the expressions, such as using fingers, using objects, and drawing pictures (MP2).

### Required Materials

Materials to Gather

Materials to Copy

• Number Mat 1–5
• Roll and Add Stage 2 Recording Sheet

### Launch

• Groups of 2
• Give each group of students a number mat and access to connecting cubes or two-color counters. Give each student a recording sheet.
• “Vamos a aprender una nueva forma de trabajar en el centro ‘Lanza y suma’” // “We are going to learn a new way to play the Roll and Add center.”
• Display the recording sheet and the number mat.
• “Debo lanzar 2 cubos sobre el tablero. Voy a usar los números que obtenga para escribir una expresión” // “I need to roll 2 cubes onto the mat. I’ll use the numbers to fill in an expression.”
• Demonstrate rolling 2 cubes and filling in an expression.
• “Ahora mi compañero y yo debemos encontrar juntos el valor de la expresión. ¿Qué podemos hacer para encontrar el valor de las expresiones?” // “Now my partner and I need to work together to find the value of the expression. What can we do to find the value of the expressions?” (You can use your fingers. You can use objects. You can draw a picture.)
• Invite 2 students to demonstrate methods to find the value of the expression.
• Demonstrate writing the total on the line.
• “Con su compañero, lancen 2 cubos, escriban una expresión y encuentren el valor de la expresión. Por turnos, lancen los cubos” // “Work with your partner to roll 2 cubes, fill in an expression, and find the value of the expression. Take turns rolling.”

### Activity

• 7 minutes: partner work time
• Monitor for students who use the methods listed in the activity narrative to find the value of expressions.

### Activity Synthesis

• Invite a student who used their fingers to find the value an expression to share.
• Invite a student who used objects to find the value of an expression to share.
• Invite a student who drew a picture to find the value of an expression to share.
• After each student shares, ask students where they see each number in the expression in the representation.

## Activity 2: Encontremos el valor de expresiones (10 minutes)

### Narrative

The purpose of this activity is for students to find the value of addition and subtraction expressions.

MLR8 Discussion Supports. Invite students to say each expression aloud. Listen for and clarify any questions about the expressions.
Action and Expression: Develop Expression and Communication. Some students may benefit from using 5-frames to find the value of the expression. Give students access to 5-frames so that they can use two-color counters and a 5-frame to represent each expression.
Supports accessibility for: Organization, Conceptual Processing

### Required Materials

Materials to Gather

### Launch

• Groups of 2
• Write and display $$4 - 2$$.
• “Encuentren el valor de $$4 - 2$$.” // “Find the value of $$4 - 2$$.”
• 1 minute: independent work time
• “Muéstrenle a su compañero cómo encontraron el valor de $$4 - 2$$. ¿En qué se parecen y en qué son diferentes las formas como encontraron el valor de la expresión?” // “Show your partner how you found the value of $$4 - 2$$. What is the same and what is different about how you found the value of the expression?” (We both showed 4 things first and we both took away 2 things. One of us put down 2 fingers and one took off 2 counters.)
• 1 minute: partner discussion
• Share responses.
• $$4 - 2$$ es 2.” // $$4 - 2$$ is 2.”
• “Encuentren el valor de cada expresión con su compañero. Escriban sus respuestas sobre la línea que está al lado de cada expresión” // “Work with your partner to find the value of each expression. Write your answers on the line next to each expression.”

### Activity

• 6 minutes: partner work time

### Student Facing

$$3 + 1$$

$$6 - 3$$

$$5 - 4$$

$$7 + 2$$

$$5 + 0$$

$$9 - 4$$

### Student Response

If students find a value other than 5 for $$9 - 4$$, consider asking:

• “¿Puedes usar estos cubos encajables para mostrar la expresión? ¿Cómo te pueden ayudar los cubos a encontrar el valor de la expresión?” // “Can you use these connecting cubes to show the expression? How can the cubes help you find the value of the expression?”

### Activity Synthesis

• “¿Cómo pueden ayudarnos nuestros dedos a encontrar el valor de una expresión?” // “How can our fingers help us find the value of an expression?”
• “¿Cómo pueden ayudarnos las fichas a encontrar el valor de una expresión?” // “How can counters help us find the value of an expression?”
• “¿Cómo puede hacer un dibujo ayudarnos a encontrar el valor de una expresión?” // “How can drawing a picture help us find the value of an expression?”

## Activity 3: Centros: Momento de escoger (20 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that offer practice with addition and subtraction story problems and expressions, as well as writing numbers.

• Shake and Spill
• Number Race
• Math Stories

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from:
• Roll and Add, Stages 1 and 2
• Shake and Spill, Stages 1-3
• Number Race, Stage 1
• Math Stories, Stages 1 and 2

### Launch

• “Hoy vamos a escoger centros de los que ya conocemos” // “Today we are going to 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.

Lanza y suma

Revuelve y saca

Carrera con números

Historias matemáticas

### Activity Synthesis

• “¿En qué han mejorado que antes fuera retador para ustedes? ¿Qué hicieron para mejorar?” // “What is something that used to be challenging for you that you’ve gotten better at? What did you do to help yourself improve?”

## Lesson Synthesis

### Lesson Synthesis

Display $$4 - 1$$.

“Cuéntenle a su compañero 2 formas diferentes de encontrar el valor de esta expresión” // “Tell your partner 2 different ways that you can find the value of this expression.”