# Lesson 17

Formemos 10 para sumar

## Warm-up: Cuántos ves: Tableros de 10 dobles (10 minutes)

### Narrative

The purpose of this How Many Do You See is for students to subitize or use grouping strategies to describe the images they see.

When students use grouping strategies to visualize the quantities in the $$10 + n$$ structure they come to see that some can be taken from one group and added to the other to make a ten and some more (MP7).

### Launch

• Groups of 2
• “¿Cuántos ven? ¿Cómo lo saben?, ¿qué ven?” // “How many do you see? How do you see them?”
• Flash the image.
• 30 seconds: quiet think time

### Activity

• Display the image.
• “Discutan con su pareja cómo pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.
• Repeat for each image.

### Student Facing

¿Cuántos ves?
¿Cómo lo sabes?, ¿qué ves?

### Activity Synthesis

• “¿Alguien puede expresar con otras palabras la forma en la que _____ vio los puntos?” // “Who can restate the way _____ saw the dots in different words?”

## Activity 1: El juego de 9 más algo (20 minutes)

### Narrative

The purpose of this activity is for students to find sums when one addend is nine. Students represent sums on the 10-frame to encourage them to use the structure of a ten. During the launch, the teacher demonstrates playing a round of the game. It is important to let students discover patterns as they play the game. For example, when finding the sum of $$9 + 5$$, some students may represent each addend on a separate 10-frame and count to find the sum. Other students may use the associative property and move one counter from the five, and add it to the nine to make a ten.

Students may generalize that when they take one from an addend to make 10, the sum has one less one than that addend. When students build this understanding, they may no longer need to show their thinking on the 10-frame and can just write an equation. By repeatedly making the ten by taking one from an addend, students may see and use the structure of ten to add on (MP7, MP8).

Engagement: Internalize Self-Regulation. Synthesis: Provide students an opportunity to self-assess and reflect on their own progress. For example, ask students how comfortable they are adding different numbers to 9.
Supports accessibility for: Conceptual Processing, Organization

### Required Materials

Materials to Gather

### Required Preparation

• Each group of 2 needs a set of Number Cards (0-10).

### Launch

• Groups of 2
• Give each group a set of number cards and access to double 10-frames and connecting cubes or two-color counters.
• “Vamos a jugar ‘9 más algo’. En este juego, le sumamos distintos números a 9 y anotamos con ecuaciones lo que pensamos. Juguemos la primera ronda juntos” // “We are going to play the 9 Plus game. In this game, we add different numbers to 9 and record our thinking with equations. Let’s play the first round together.”
• Demonstrate displaying 9 counters on the double 10-frame to start the game.
• “Ahora tomamos una tarjeta de números. Le agrego ese número de fichas a 9 y averiguo la suma” // “Now we pick a number card. I add that many counters to 9 and figure out the sum.”
• Demonstrate placing each counter on the empty 10-frame.
• “¿Cuál es la suma? ¿Cómo lo saben? ¿Qué ecuación puedo escribir para mostrar el total?” // “What is the sum? How do you know? What equation can I write to show the total?” (The sum is 13. I counted on from 9. We could move 1 from the 4 to the 9 to make 10 and then there are 3 more. $$9 + 4 = 13$$ or $$10 + 3 = 13$$)
• 30 seconds: quiet think time
• Share and record responses.

### Activity

• “Hablen con su compañero sobre los patrones que observan mientras juegan el juego” // “Talk with your partner about the patterns you notice as you play the game.”
• 8 minutes: partner work time

### Student Facing

• Pon 9 fichas.
• Toma una tarjeta de números y agrega esa cantidad de fichas.
• Escribe una ecuación para representar las fichas.
¿Puedes escribir más de una?

Ecuaciones:

Ronda 1: ________________________________

Ronda 2: ________________________________

Ronda 3: ________________________________

Ronda 4: ________________________________

Ronda 5: ________________________________

### Activity Synthesis

• “¿Qué patrones observaron cuando jugaron el juego?” // “What patterns did you notice as you played the game?” (I saw that any $$9 +$$ expression can be written as a $$10 +$$ expression. You can take one from the other addend. The nine goes up by one and the other addend goes down by one.)
• “Podemos escribir la ecuación $$9 + 5 = 10 + 4$$ para representar el hecho de que las expresiones son iguales” // “We can write the equation $$9 + 5 = 10 + 4$$ to represent that the expressions are equal.”

## Activity 2: Las aves de Clare (15 minutes)

### Narrative

The purpose of this activity is for students to solve addition story problems in which one addend is close to 10. Students may use any method or representation that makes sense to them. During the synthesis, the double 10-frame is used to visually show decomposing one addend to make ten with the other (the associative property).

MLR7 Compare and Connect. Synthesis: After all methods have been presented, lead a discussion comparing, contrasting, and connecting the different approaches. Ask, “¿En qué se parecen estas estrategias? ¿En qué son diferentes?” // “How are the different strategies similar? How are they different?”

### 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
• 3 minutes: partner discussion
• Monitor for students who use these methods:
• shows 6, shows 8 more, and counts all
• shows 8, and counts on 6
• shows 6, adds 4 to make 10, adds 4 more
• shows 8, adds 2 to make 10, adds 4 more

### Student Facing

1. Clare dibuja algunas aves.
Ella dibuja 3 aves en un nido y 9 aves volando.
¿Cuántas aves dibujó?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: ________________________________

2. Clare dibuja aves de clima cálido.
Ella dibuja 6 tucanes y 8 loros.
¿Cuántas aves dibujó?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: ________________________________

3. Clare dibuja aves de clima frío.
Ella dibuja 7 pingüinos y 5 búhos.
¿Cuántas aves dibujó?
Muestra cómo pensaste. Usa dibujos, números o palabras.

Ecuación: ________________________________

### Activity Synthesis

• Invite previously identified students to share in the sequence above.
• “¿Qué hizo _____ para representar el problema?” // “What did _____ do to represent the problem?”
• Record each method with an equation.
• 6 + 8 = 14
• 8 + 6 = 14
• 6 + 4 = 10, 10 + 4 = 14
• 8 + 2 = 10, 10 + 4 = 14

## Lesson Synthesis

### Lesson Synthesis

“Hoy vimos que formar una decena puede ayudarnos a sumar números hasta 20” // “Today, we saw that making a ten can help us add numbers within 20.”

Display the double 10-frame with nine red counters.

“Si sumo siete, ¿cómo podríamos anotar la suma con una ecuación?” // “If I add seven, how could we record the sum with an equation?” ($$9 + 7 = 16$$, $$10 + 6 = 16$$)

“¿Cómo puedo escribir una ecuación para mostrar que estas dos expresiones son equivalentes?” // “How can I write one equation to show that these two expressions are equivalent?” ($$9 + 7 = 10 + 6$$)