# Lesson 12

Maneras de representar situaciones de medidas

## Warm-up: Observa y pregúntate: La feria (10 minutes)

### Narrative

The purpose of this warm-up is to elicit the idea that there are many mathematical contexts at a state or county fair, and to familiarize students with some possible situations before they solve problems in upcoming activities.

### Launch

• Groups of 2
• Display the images.
• “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?”
• 1 minute: quiet think time

### Activity

• “Discutan con su compañero lo que pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses.

### Student Facing

¿Qué observas? ¿Qué te preguntas?

### Activity Synthesis

• “En las siguientes lecciones, vamos a resolver problemas que pueden surgir en una feria. ¿Qué actividades puede haber en una feria?” // “In the next few lessons, we are going to solve problems that might come up at a fair. What are some activities that could be at a fair?” (carnival rides and games, food, animals in barns, concerts with music, shows)
• “¿Dónde pueden ver matemáticas en la feria?” // “Where might you see math at the fair?” (We needed money to buy things or buy tickets for rides. They weighed things like vegetables and animals.)

## Activity 1: Concurso de calabazas gigantes (20 minutes)

### Narrative

The purpose of this activity is for students to solve problems involving weights that are given in the same units. Students begin by generating mathematical questions about an image of two giant pumpkins. Then, weights are given for each pumpkin and students narrow down the questions that could be answered with this information. Students then solve one of the problems generated by the class. Students can all solve the same problem or each group could solve a different problem. As students are generating questions that can be answered, decide which option makes the most sense for your class.

### Launch

• Groups of 2

MLR5 Co-Craft Questions

• Display the image.
• “Escriban una lista de preguntas matemáticas que se pueden hacer sobre esta imagen” // “Write a list of mathematical questions that could be asked about this image.”
• 1 minute: independent work time
• 1–2 minutes: partner discussion
• If students don’t generate questions that involve weight or liquid volume, consider asking: “¿Qué preguntas matemáticas podríamos hacer sobre el peso (o el volumen líquido)?” // “What are some mathematical questions we could ask that involve weight (or liquid volume)?”
• Invite several students to share one question with the class. Record responses.

### Activity

• “En el concurso de calabazas gigantes de la feria, se pesan las calabazas para ver cuál es la más pesada. La calabaza más pesada gana. La calabaza más pequeña pesa 276 kg. La calabaza más grande pesa 347 kg” // “At the giant pumpkin event at the fair, they weigh the pumpkins to see which is the heaviest. The heaviest pumpkin wins. The smaller pumpkin weighs 276 kg. The larger pumpkin weighs 347 kg.”
• Record weights for all to see.
• “Ahora que conocemos el peso de cada calabaza, ¿qué preguntas matemáticas podríamos responder?” // “Now that we know the weight of each pumpkin, what mathematical questions could we answer?” (How much more does the heavier pumpkin weigh? How much less does the lighter pumpkin weigh? How much do the pumpkins weigh together?)
• 2 minutes: partner discussion
• Share and record responses.
• Give each group tools for creating a visual display.
• Have each group create a poster for one of the problems the class came up with. Decide whether the class will solve the same problem or if there is enough variety to have groups solve different problems.
• 5 minutes: partner work time

### Student Facing

1. Escribe una lista de preguntas matemáticas que se pueden hacer sobre esta imagen.
2. Con su compañero, resuelvan el problema que el profesor les asignó. Muestren en un póster cómo pensaron. Asegúrense de escribir en el póster el problema que están resolviendo.

### Activity Synthesis

• Display student posters around the room. If students solved different problems, group them by problem solved.
• 5 minutes: gallery walk
• If students solved the same problem, ask:
• “¿En qué se parecen y en qué se diferencian las formas en las que se representó este problema en los pósteres?” // “What is the same and what is different about how this problem was represented on the posters?”
• If students solve different problems, ask:
• “¿Qué conexiones observan entre las formas en las que se representaron estos problemas?” // “What connections do you notice about how these problems are represented?”

## Activity 2: Clasificación de tarjetas: Calabazas gigantes (15 minutes)

### Narrative

The purpose of this activity is for students to make sense of representations of situations involving weights and liquid volumes. Students are reminded that tape diagrams can be used to represent relationships between quantities in different types of problems.

As students analyze descriptions of situations and make connections across representations, they practice looking for and making use of structure (MP7). As they relate the numbers and relationships in situations to those in diagrams, they reason quantitatively and abstractly (MP2).

MLR8 Discussion Supports. Activity: Students should take turns finding a match and explaining their reasoning to their partner. Display the following sentence frames for all to see: “Observé _____, entonces emparejé . . .” // “I noticed _____, so I matched . . . .” Encourage students to challenge each other when they disagree.
Engagement: Develop Effort and Persistence. Chunk this task into more manageable parts. Give students a subset of the cards to start with and introduce the remaining cards once students have completed their initial set of matches.
Supports accessibility for: Organization, Social-Emotional Functioning

### Required Materials

Materials to Copy

• Card Sort: Giant Pumpkins, Spanish

### Required Preparation

• Create a set of cards from the blackline master for each group of 2.

### Launch

• Groups of 2
• Give one set of pre-cut cards to each group of students.

### Activity

• “Este grupo de tarjetas tiene situaciones y diagramas. Con su compañero, emparejen cada situación con un diagrama que la represente. Prepárense para explicar cómo hicieron sus parejas” // “This set of cards includes situations and diagrams. Work with your partner to match each situation to a diagram that represents it. Be prepared to explain your matches.”
• 8 minutes: partner work time

### Student Facing

Tu profesor te dará un grupo de tarjetas con descripciones y diagramas. Empareja cada descripción con un diagrama que represente la misma situación.

### Activity Synthesis

• Display diagram C and situation I.
• “¿Cómo saben que este diagrama corresponde a esta situación?” // “How do you know this diagram matches this situation?” (The 7 in the diagram represents each pack of seeds weighing 7 grams. The 84 shows that all the seed packs weigh 84 grams. The dotted lines in the diagram shows that we don’t know how many seed packs there are.)
• “¿Qué ecuaciones podemos escribir que correspondan a este diagrama?” // “What equations could we write to match this diagram?” ($${?}\times7=84$$ or $$84\div7={?}$$)
• Discuss how students know that diagram B and situation E are a match and how the situation could be represented with equations.
• Attend to the language that students use in their explanations, giving them opportunities to describe the situations and diagrams more precisely.

## Lesson Synthesis

### Lesson Synthesis

“Hoy resolvimos problemas sobre peso y volumen líquido relacionados con calabazas gigantes. ¿Qué les ayuda a darle sentido a estos problemas?” // “Today we solved problems about weight and liquid volume related to giant pumpkins. What helps you make sense of such problems?” (It helps to think about what is happening in the situation and relate the weights or liquid volumes to what I know, like how heavy 1 kilogram is or how much 1 liter is.)

“¿Qué representaciones les gusta usar cuando resuelven problemas que involucran peso o volumen líquido?” // “What representations do you like to use when solving problems involving weight or liquid volume?” (When I am adding and subtracting, I like to use a number line, tape diagram, or just equations. When I am multiplying or dividing, I draw equal groups or base-ten block drawings.)