Lesson 19

The purpose of this Choral Count is to invite students to practice counting by 10 and notice patterns in the count. These understandings help students develop fluency with the count sequence and will be helpful as students begin working with numbers beyond 10.

• “Cuenten de 10 en 10, comenzando en 0” // "Count by 10, starting at 0."
• Record as students count.
• Stop counting and recording at 100.
• “Cuenten hacia atrás de 10 en 10, comenzando en 100” // "Count backward by 10, starting at 100."
• Record as students count.
• Stop counting and recording at 0.

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

• “¿Cómo sabían qué número vendría después cuando contaban hacia atrás?” // "How did you know what number would come next as you counted backward?"

The purpose of this activity is for students to write two equations to match each story problem. Students solve the problems in any way that makes sense to them. They may write an equation in which the total is before the equal sign, or that uses the add in any order property. Students may write equations with a box around the answer, an empty box for the unknown, or a combination of both.

The story problems in this activity are about the Mexican game, Lotería. During the launch, students learn how the game is played and some similarities between Lotería and Bingo. Before sharing information about the game, ask students if anyone has heard of this game, and what they know about how it is played. Consider showing students pictures of Lotería boards and cards.

• Groups of 2
• Give students access to connecting cubes or two-color counters.
• “Hemos resuelto problemas sobre diferentes juegos que juega la gente. Hoy resolveremos problemas sobre un juego que se llama Lotería. ¿Alguien ha jugado Lotería?” // “We have been solving problems about different games people play. Today we will solve problems about a game called Lotería. Has anyone played Lotería?"
• Share responses.
• If needed, “Lotería es un juego muy popular en México. Es parecido al Bingo. En lugar de números, son imágenes. La persona que dirige el bingo escoge una tarjeta y dice qué imagen hay en ella. Si la imagen está en el cartón que ustedes tienen, la cubren. Muchas personas usan frijoles o piedras pequeñas para cubrir las imágenes. Cuando tienen cubiertas cuatro imágenes en línea, dicen: ‘Lotería’” // "Lotería is a very popular game played in Mexico. It is similar to the game bingo. Instead of numbers, the caller picks a card with a picture on it. If the picture is on your board, you cover it. Many people use beans or small rocks to cover the pictures. When you have four pictures covered in a row you call out, ‘Lotería!’”
• Consider displaying images of the game boards and picture cards used in the game.

• “Resolvamos problemas sobre estudiantes que juegan Lotería” // “Let’s solve some problems about students playing Lotería.”
• Read the task statement.
• 6 minutes: independent work time
• “Compartan sus ecuaciones con su compañero. Expliquen cómo corresponden a las historias” // “Share your equations with your partner. Explain how they match the stories.”
• 3 minutes: partner discussion

• Invite students to share the equations they wrote for each story problem and explain how they match the story.

The purpose of this activity is for students to make sense of story problems that do not include a question. In some story types, like Add To, Change Unknown, students can infer what the question in the story is without it being asked. In problem types like Compare, there are multiple questions that can be answered, all of which have different equations, solutions, and methods of solving. In presenting students with problems without questions, they strengthen their understanding of connections between story problems and the equations that match. When students formulate their own questions they need to make sense of the given information in order to understand what is given and what is unknown (MP1).

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

• “Ahora van a leer problemas-historia que no tienen una pregunta. Su tarea es escribir una pregunta para cada problema. Después, resuelvan cada problema” // "Now you will read story problems that don't have a question. Your job is to write a question for each problem. Then solve the problem."
• 5 minutes: independent work time
• “Compartan su pregunta y su ecuación con su compañero” //  “Share your question and equation with your partner.”
• 3 minutes: partner discussion
• Monitor for students who wrote different questions for the problem with Diego and Noah.

• Invite previously identified students to share.
• Display the equations:
  • \(2 + 9 = \boxed{\phantom{11}}\)
  • \(9 - 2 = \boxed{\phantom{7}}\)
  • \(2 + \boxed{\phantom{7}} = 9\)
• “¿Qué pregunta representa cada una de estas ecuaciones? ¿Cómo lo saben?” // “Which question does each of these equations represent? How do you know?”