# Lesson 9

Expresiones y ecuaciones

## Warm-up: Conteo grupal: Anotar hasta 19 (10 minutes)

### Narrative

The purpose of this Choral Count is to invite students to count to 19 and notice patterns in the count. Recognizing these patterns may help students remember how to write teen numbers. Students often reverse the digits due to how we say the teen numbers.

### Launch

• “Cuenten de uno en uno, empezando en 0” // “Count by ones, starting at 0.”
• Record as students count.
• Stop counting and recording at 19.

### Activity

• “¿Qué patrones ven?” // “What patterns do you see?”
• 1–2 minutes: quiet think time
• Record responses.

### Activity Synthesis

• “Si quisiéramos contar hacia adelante desde 10, ¿qué número diríamos después de 10? ¿Cómo lo saben?” // “If we wanted to count on from 10, what number would we say after 10? How do you know?” (11 because 11 is one more than 10 and comes after 10 when we count.)

## Activity 1: Organicemos expresiones y números (15 minutes)

### Narrative

The purpose of this activity is for students to make connections between written numbers and expressions. In the activity synthesis, students see each teen number written as an equation. In this unit, when reading equations to students, read the equal sign as “es” // “is.” For example, read $$10 + 3 = 13$$ as “10 más 3 es 13” // “10 plus 3 is 13.” The equal sign will be read as “es igual a” // “equals” in the next unit.

MLR8 Discussion Supports. Synthesis: At the appropriate time, give students 2–3 minutes to make sure that everyone in their group can explain how they organized the numbers and expressions. Invite groups to rehearse what they will say when they share with the whole class.
Engagement: Develop Effort and Persistence. Some students would benefit from having clear examples of the expectation of group work in this activity. Invite students to generate a list of shared expectations for group work. Ask students to share explicit examples of what those expectations would look like in this activity.
Supports accessibility for: Social-Emotional Functioning

### Required Materials

Materials to Copy

• Numbers and Expressions Cards

### Required Preparation

• Create a set of cards from the blackline master for each group of 4.

### Launch

• Groups of 4
• Give each group of students a set of cards.
• “Con su grupo, organicen las tarjetas de una forma que tenga sentido para ustedes” // “Work with your group to organize the cards in a way that makes sense to you.”

### Activity

• 6 minutes: small-group work time
• Monitor for students who organize the numbers and expressions as shown in the sample response.

### Activity Synthesis

• Invite a group of students to share how they organized the numbers and expressions or display the image in student responses.
• “¿Qué observan sobre los números y las expresiones cuando están organizados de esta forma?” // “What do you notice about the numbers and expressions when they are arranged this way?” (They’re in the order that we count. The first number stays the same. The second number is 1 more each time. All the expressions have a 10. The second number starts at 1 and is one more each time. The expressions match the numbers.)
• “¿Cuál número es representado por $$10 + 1$$? ¿Cómo lo saben?” // “Which number does $$10 + 1$$ represent? How do you know?” (11)
• $$10 + 1$$ es 11. Podemos escribir eso como $$10 + 1 = 11$$” // $$10 + 1$$ is 11. We can write that as $$10 + 1 = 11$$.”
• Demonstrate writing equations for each number and expression.

## Activity 2: Ecuaciones y tableros de 10 (10 minutes)

### Narrative

The purpose of this activity is for students to match equations to numbers 11–19 presented on 10-frames. During the synthesis, students focus on each part of the equation and where it can be seen in the 10-frame representation of the number. When students see different parts of the equations in the 10-frame images, they look for and make use of structure (MP7).

### Launch

• Groups of 2
• “Unan con una línea cada ecuación con los puntos que corresponden” // “Draw a line from each equation to the dots it matches.”

### Activity

• 2 minutes: independent work time
• 3 minutes: partner work time

### Student Facing

$$10+9=19$$

$$10+1=11$$

$$10+4=14$$

$$10+8=18$$

$$10+5=15$$

$$10+2=12$$

### Activity Synthesis

• Invite a student to share which image matches $$10 + 5 = 15$$.
• “¿En qué parte del tablero de 10 ven 15?” // “Where do you see 15 on the 10-frame?” (There are 15 dots altogether.)
• “En qué parte del tablero de 10 ven $$10 + 5$$?” // “Where do you see $$10 + 5$$ on the 10-frame?” (There are 10 dots on the 10-frame and 5 dots under the 10-frame.)

## Activity 3: Conozcamos “Formar o separar números: Números del 11 al 19” (20 minutes)

### Narrative

The purpose of this activity is for students to learn stage 2 of the Make or Break Apart Numbers center. Students find 2 groups on their gameboard that make a given number and record the composition with an expression. After they participate in the center, students choose from any stage of previously introduced centers.

• Bingo
• Number Race
• Grab and Count
• Tower Build

### Required Materials

Materials to Gather

Materials to Copy

• Make or Break Apart Numbers Stage 2 Number Mat 11-19
• Make or Break Apart Numbers Stage 2 Gameboards
• Make or Break Apart Numbers Stage 2 Recording Sheet, Spanish

### Required Preparation

Gather materials from:

• Bingo, Stages 1-4
• Number Race, Stages 1 and 2
• Grab and Count, Stage 1
• Tower Build, Stages 1 and 2

### Launch

• Groups of 2
• Give each group of students two-color counters, 1 connecting cube, and a number mat. Give each student a recording sheet and a gameboard.
• “Vamos a aprender una nueva forma de trabajar en el centro ‘Formar o separar números’” // “We are going to learn a new way to do the Make or Break Apart Numbers center.”
• “Voy a lanzar un dado en el tablero numérico para encontrar qué número tengo que formar” // “I’m going to roll a cube onto the number mat to find which number I have to make.”
• Demonstrate rolling the connecting cube onto the number 13.
• Display the gameboard.
• “Sacamos el número 13. Mi pareja y yo tenemos que encontrar 2 grupos que si se juntan forman 13. ¿Cuáles grupos si se juntan forman 13?” // “We rolled the number 13. My partner and I have to find 2 groups that go together to make 13. Which groups go together to make 13?”
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Share responses.
• “Voy a poner una ficha en este grupo de 10 puntos y una ficha en este grupo de 3 dedos. 10 y 3 es 13. ¿Qué expresión debo escribir en mi hoja de registro?” // “I’m going to put a counter on this group of 10 dots and a counter on this group of 3 fingers. 10 and 3 is 13. What expression should I write on my recording sheet?” ($$10 + 3$$)
• 30 seconds: quiet think time
• Share responses.
• Demonstrate writing $$10 + 3$$.
• “Ahora que mi pareja y yo escribimos nuestra expresión, podemos ver si hay 2 grupos más que si se juntan forman 13. Si no podemos encontrar más maneras de formar 13, lanzamos los dados y formamos otro número” // “Now that my partner and I have written our expression, we can look to see if there are 2 more groups that go together to make 13. If we can’t find any more ways to make 13, then we roll and make another number.”
• “Tomen turnos con su pareja para encontrar 2 grupos que formen un número y anotar una expresión” // “Take turns with your partner to find 2 groups to make a number and write an expression.”

### Activity

• 8 minutes: partner work time
• “Ahora pueden escoger otro centro. También pueden seguir jugando ‘Formar o separar números’” // “Now you can choose another center. You can also continue playing Make or Break Apart Numbers.”
• Display the center choices in the student book.
• Invite students to work at the center of their choice.
• 10 minutes: center work time

### Student Facing

Escoge un centro.

Bingo

Carrera con números

Agarra y cuenta

Formar o separar números

Construcción de torres

### Activity Synthesis

• “En los centros trabajamos con números del 11 al 19. Cuéntenle a su pareja dos cosas que saben sobre estos números” // “We worked with numbers 11-19 in centers. Tell your partner two things that you know about these numbers.”

## Lesson Synthesis

### Lesson Synthesis

Display 14 dots on a 10-frame and:

• the number 14
• 10 and 4
• $$10 + 4$$
• $$10 + 4 = 14$$
“¿Cuál de estas corresponde al tablero de 10? ¿Cómo lo saben?” // “Which of these matches the 10-frame? How do you know?” (They all match the 10-frame. There are 14 dots. There are 10 dots on the 10-frame and 4 more dots.)