# Lesson 13

Más problemas-historia con números del 11 al 19

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

### Narrative

The purpose of this Number Talk is to elicit strategies and understandings students have for adding to teen numbers. These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to find the missing value in an equation with a teen number.

When students add ones to ones, they are making use of the structure of the base-ten number system (MP7).

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

### Student Facing

Encuentra mentalmente el valor de cada expresión.

• $$3 + 4$$
• $$4 + 3$$
• $$10 + 3$$
• $$14 + 3$$

### Activity Synthesis

• “¿Cómo nos ayuda saber el valor de $$4 + 3$$ a encontrar el valor de $$14 + 3$$?” // “How does knowing $$4 + 3$$ help you with $$14 + 3$$?” (You can add $$4 + 3$$ and then add 10 more.)

## Activity 1: Sentados o de pie (15 minutes)

### Narrative

The purpose of this activity is for students to solve a Take From, Change Unknown story problem using a method that makes sense to them. This is a challenging problem type for students because the amount that students are taking away or counting on is the unknown. The activity begins with a numberless and questionless story problem to help students understand the context and structure of the story problem. Students begin the activity by looking at the problem displayed, rather than in their books. The numbers 5, 10, and 15 are used so that the focus of the activity can be on making sense of the story problem, rather than the computation. Students may benefit from acting out the story.

### Required Materials

Materials to Gather

### Launch

• Groups of 2
• Give students access to double 10-frames and connecting cubes or two-color counters.
• Display and read the numberless and questionless story problem.
• “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?”
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Record responses.
• If needed, “¿Qué pregunta podemos hacer?” // “What question could we ask?”

### Activity

• “Pasen la página y miren el siguiente problema” // “Turn the page and look at the next problem.”
• Read the complete story problem.
• 3 minutes: independent work time
• 2 minutes: partner discussion
• Monitor for students who:
• Show 15 on the 10-frames and make 5 a different color to represent the students who are still standing. The student counts the remaining counters, or just see that there are 10. ($$15 - 5 = \boxed{10}$$)
• Draw 15 objects and cross out until there are 5 left. Count how many are crossed out. $$15 - \boxed{10} = 5$$
• Take away 5 from 15 (14, 13, 12, 11, 10) ($$15 - 5 = \boxed{10}$$).

### Student Facing

1. Hay estudiantes de pie en el salón de clase.
Algunos de los estudiantes se sientan en la alfombra.
Todavía hay algunos estudiantes de pie.
2. Hay 15 estudiantes de pie en el salón de clase.
Algunos estudiantes se sientan en la alfombra.
5 estudiantes se quedan de pie.
¿Cuántos estudiantes se sentaron en la alfombra?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: ________________________________

### Activity Synthesis

• Invite previously identified students to share.
• “¿Cómo muestra este método el problema-historia?” // “How does this method show the story problem?” (I can see 15 for the number they started with. 10 is how many students sat down on the rug. 5 is how many students are still standing.)
• “Recuerden dibujar un cuadro alrededor de su respuesta cuando resuelvan y escriban una ecuación” // “Remember to put a box around your answer when you solve and write an equation.”

## Activity 2: Resolvamos problemas-historia y comparemos métodos (10 minutes)

### Narrative

The purpose of the lesson is for students to solve a Take From, Result Unknown and a Take From, Change Unknown story problem. The story problems have the same numbers, which include a teen number, so that the focus can be on the structure of the story problems and the equations. In the activity synthesis students compare the structure of the problems and in the lesson synthesis, students make sense of equations that represent the story problems (MP2).

MLR2 Collect and Display. Circulate, listen for, and collect the language students use as they talk about their solution strategies. On a visible display, record words and phrases such as: ”conté hacia atrás” // “counted back” and “ecuación”// “equation”. Invite students to borrow language from the display as needed, and update it throughout the lesson.
Action and Expression: Internalize Executive Functions. Invite students to plan a method, including the tools they will use, for solving the story problems. If time allows, invite students to share their plan with a partner before they begin.
Supports accessibility for: Organization, Conceptual Processing

### Required Materials

Materials to Gather

### Launch

• Groups of 2
• Give students access to double 10-frames and connecting cubes or two-color counters.

### Activity

• 4 minutes: independent work time
• “Compartan con su pareja cómo pensaron” // “Share your thinking with your partner.”
• 2 minutes: partner discussion

### Student Facing

1. Hay 17 estudiantes en el salón.
4 estudiantes se van a casa.
¿Cuántos estudiantes están todavía en el salón?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: _____________________________
2. Hay 17 estudiantes en el salón.
Algunos estudiantes se van a casa.
Ahora hay 4 estudiantes en el salón.
¿Cuántos estudiantes se fueron a casa?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: _____________________________

### Activity Synthesis

• ¿En qué se parecen y en qué son diferentes los dos problemas-historia?” // “How are the two story problems the same and different?” (They have the same numbers. In one of them we know how many to take away and in the other one we have to figure out how many to take away.)

## Activity 3: Centros: Momento de escoger (15 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that offer practice adding and subtracting within 10. Students choose from any stage of previously introduced centers.

• Shake and Spill
• Compare
• Number Puzzles

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from previous centers:
• Shake and Spill, Stages 3-5
• Compare, Stage 1
• Number Puzzles, Stage 1

### Launch

• Groups of 2
• “Ahora van a escoger un centro de los que ya conocemos” // “Now you 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.”
• 30 seconds: quiet think time

### Activity

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

### Student Facing

Escoge un centro.

Revuelve y saca

Compara

Acertijos numéricos

### Activity Synthesis

• Display twelve red counters and cover five yellow counters with a cup.
• “Estamos jugando con diecisiete fichas. ¿Cuántas fichas están debajo del vaso? ¿Cómo lo saben?” // “We are playing with seventeen counters. How many yellow counters are under the cup? How do you know?”

## Lesson Synthesis

### Lesson Synthesis

“Hoy comparamos dos tipos diferentes de problemas-historia” // “Today we compared two different types of story problems.”

Display stories and equations from the activity about students leaving the classroom.

$$17 - 4 = \boxed{\phantom{3}}$$

$$17 - \boxed{\phantom{3}} = 4$$

¿Qué pregunta se respondía con la primera ecuación?” // What question was the first equation answering?” (How many students are still in the classroom?)

“¿Qué pregunta se respondía con la segunda ecuación?” // “What question was the second equation answering?” (How many students went home?)

“¿Por qué el cuadro está en posiciones diferentes?” // “Why is the box in different places?” (They are answering different questions. The unknown part of the story is different.)

## Student Section Summary

### Student Facing

Aprendimos que 10 unidades forman una decena.

Aprendimos que todos los números del 11 al 19 se pueden representar como una decena y algunas unidades.

Usamos esa comprensión para encontrar números desconocidos en ecuaciones de suma y de resta con números del 11 al 19.

$$10 + \boxed{\phantom{6}} = 16$$

$$10 + 2 = \boxed{\phantom{6}}$$​​​​​​

$$5 + \boxed{\phantom{6}} = 15$$

$$13 - 10 = \boxed{\phantom{6}}$$​​​​​​

$$19 - 9 = \boxed{\phantom{6}}$$​​​​​​

Resolvimos un nuevo tipo de problema-historia en el que no sabemos cuántos restar. Usamos varias ecuaciones para mostrar la historia.

Hay 17 estudiantes en el salón.
Algunos estudiantes se van a casa.
Ahora hay 4 estudiantes en el salón.
¿Cuántos estudiantes se fueron a casa?

$$17 - \boxed{\phantom{3}} = 4$$

$$17 - 4 = \boxed{\phantom{6}}$$