# Lesson 18

Contemos problemas-historia a partir de expresiones (optional)

## Warm-up: Conteo grupal: Contemos hasta 50 y contemos empezando en un número (10 minutes)

### Narrative

The purpose of this warm-up is to extend the verbal count sequence to 50 and to count on from a given number. As students count, point to the numbers posted so that students can follow along. If students struggle to count on, consider asking “¿Cuál número va después del 4?” // “What number comes after 4?” or providing a running start by counting “1, 2, 3…” and having students continue the count.

### Launch

• “Contemos hasta 50” // “Let’s count to 50.”
• Count to 50.
• Repeat 1-2 times.

### Activity

• “Practiquemos cómo contar hacia adelante. Empecemos en el 4 y contemos hasta 20” // “Let’s practice counting on. Start at 4 and count up to 20.”
• Count on from 4 to 20.
• Repeat 3–4 times starting with other numbers within 20.

### Activity Synthesis

• “Si quisiéramos contar hacia adelante desde el 5 hasta 20, ¿cuál número diríamos después del 5? ¿Cómo lo saben?” // “If we wanted to count on from 5 to 20, what number would we say after 5? How do you know?” (6 because 6 is one more than 5 and comes after 5 when we count.)

## Activity 1: Comparte un problema-historia que corresponda a una expresión (10 minutes)

### Narrative

The purpose of this activity is for students to tell a story problem that matches a given expression.

MLR8 Discussion Supports. Invite students to use gestures with verbal descriptions and drawings to tell the story problem.
Advances: Listening, Representing, Speaking, Conversing
Engagement: Internalize Self-Regulation. Provide students an opportunity to self-assess and reflect on their story problem. For example, their story problem should have a question and the numbers should match the ones in their expression.
Supports accessibility for: Organization, Memory, Attention

### Launch

• Groups of 2
• “Piensen en una expresión. Pueden pensar en una expresión de suma o en una expresión de resta” // “Think of one expression. You can think of an addition expression or a subtraction expression.”
• 1 minute: independent work time
• “Compartan su expresión con su compañero. Escriban en el recuadro la expresión que su compañero les comparta” // “Share your expression with your partner. Write the expression that your partner shares in the box.”
• 2 minutes: partner discussion

### Activity

• “Piensen en un problema-historia que corresponda a la expresión que escribieron en el recuadro. Recuerden que un problema-historia debe tener una pregunta al final. Pueden hacer dibujos o escribir palabras y números en sus libros de trabajo como ayuda para recordar lo que ocurre en su problema-historia” // “Think of a story problem that goes with the expression that you wrote in the box. Remember that a story problem should have a question at the end. You can draw pictures or write words and numbers in your workbook to help you remember what happens in your story problem.”
• 3 minutes: independent think time
• “Compartan su problema-historia con su compañero. ¿Su historia corresponde a su expresión?” // “Share your story problem with your partner. Does their story match their expression?”
• 3 minutes: partner discussion

### Activity Synthesis

• “En la siguiente actividad, vamos a compartir nuestros problemas-historia con toda la clase” // “In the next activity, we will share our story problems with the whole class.”

## Activity 2: Recorrido por el salón: Problema-historia y expresión (20 minutes)

### Narrative

The purpose of this activity is for students to share story problems and figure out which expression matches a given story problem.

### Launch

• Groups of 2
• “Vamos a hacer un recorrido por el salón para escuchar los problemas-historia que todos crearon” // “We’re going to do a gallery walk to hear the story problems that everyone created.”
• “Mientras hacen el recorrido, completen una expresión para cada problema-historia que escuchen” // “As you walk around, fill in an expression for each story problem that you hear.”

### Activity

• Invite half of the class to stand and share their story problems while the other half of the class walks around.
• 7 minutes: gallery walk
• Switch groups.
• 7 minutes: gallery walk

### Student Facing

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} + \underline{\hspace{1 cm}}$$

$$\underline{\hspace{1 cm}} - \underline{\hspace{1 cm}}$$

### Activity Synthesis

• Invite 1-2 students to share their story problems.
• “¿Qué expresión corresponde al problema-historia? ¿Cómo lo saben?” // “What expression goes with their story problem? How do you know?”
• “¿Qué parte de la historia les ayudó a descubrir que necesitaban una expresión de suma/resta?” // “What in the story helped you figure out that you needed an addition/subtraction expression?”

## Activity 3: Centros: Momento de escoger (15 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. Students choose from any stage of previously introduced centers.

• Find the Value of Expressions
• Roll and Add
• Shake and Spill
• Number Race
• Math Stories

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from:
• Find the Value of Expressions, Stage 1
• 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 un centro 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” // “Think about what you would like to do.”

### Activity

• Invite students to work at the center of their choice.
• 10 minutes: center work time

### Student Facing

Escoge un centro.

Encuentra el valor de
expresiones

​​​​​​

Lanza y suma

Revuelve y saca

Historias matemáticas

Carrera con números

### Activity Synthesis

• “¿Con qué centros les gustaría trabajar en la siguiente unidad? ¿En qué tipo de centros nuevos esperan jugar?” // “What centers are you looking forward to working with during the next unit? What kind of new centers do you hope to play?”

## Lesson Synthesis

### Lesson Synthesis

“En esta unidad, aprendimos sobre la suma y la resta usando objetos, dibujos, problemas-historia y expresiones. ¿Qué le pueden enseñar a otros estudiantes sobre la suma y la resta?” // “In this unit, we learned about addition and subtraction with objects, drawings, story problems, and expressions. What can you teach another student about addition and subtraction?”