Lesson 28

This warm-up prompts students to familiarize themselves with the mathematical context for the lesson, and builds curiosity about what kinds of objects they might be able to count in their own classroom. Teachers may use the image but it is preferable to have students answer the questions based on their own classroom. The sample responses are for the image in the workbook. Student responses will differ if they use their own classroom.

• Groups of 2
• If needed, display the image.
• “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?”
• 1 minute: quiet think time

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

• “¿Qué cosas de la imagen del salón de clase pueden contar?” // “What are some things you could count in the classroom image?” (Chairs, designs on the wall, books in the bookcase)
• “Observen alrededor de nuestro salón. ¿De qué cosas tenemos más de cinco?” // “Look around our classroom. What are some things we have more than five of?” (scissors, books, desks, chairs, glue sticks, paper, markers, students)
• Record responses.
• “¿Tenemos más de diez de alguna de ellas? ¿Cómo lo saben?” // “Do we have more than ten of any of these? How do you know?“ (There are 25 kids in the class and I know we all have a pair of scissors. So that’s more than 10. Or there are 7 table baskets and there are lots more baskets in the classroom than that.)

The purpose of this activity is for students to generate, articulate, and solve their own addition and subtraction problems. They use the context of classroom objects to create story problems and represent their thinking (MP2). Students may tell a story without asking a question, so in the launch students consider a questionless word problem so the teacher can emphasize the importance of having a question when students write their own problems.

• Groups of 2
• Give students access to double 10-frames and connecting cubes or two-color counters.
• Display and read the questionless story problem.
• “¿Qué le falta a esta historia? ¿Qué tipo de preguntas podrían hacer?” // “What is this story missing? What kind of questions could you ask?” (How many pencils did they have altogether? How many more pencils does Noah have than Elena?)
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Share and record responses.
• “Hemos estado resolviendo diferentes tipos de problemas-historia. Hoy ustedes y su compañero van a escribir y a resolver problemas-historia de suma y de resta sobre objetos de nuestro salón de clase” // “We have been solving different kinds of story problems. Today, you and your partner will write and solve addition and subtraction story problems using objects we have in our classroom.”

• “El compañero A va a escoger un número menor que 20. El compañero B va a escribir un problema-historia sobre objetos que vea en el salón y va a hacer una pregunta que tenga como respuesta el número del compañero A” // “Partner A will pick a number less than 20. Partner B will use objects in the room to write a story problem and ask a question for which the number Partner A picked is the answer.”
• “Resuelvan el problema juntos y escriban una ecuación” // “Together, solve the story problem and write an equation.”
• “Intercambien roles para el problema 2” // “Switch roles for problem 2.”
• 10 minutes: partner work time
• Monitor for a variety of methods students use to add three numbers such as:
  • Count on
  • Make a 10
  • Use related facts

• “¿De cuáles de los problemas que inventaron se sienten orgullosos?” // “What were some of the problems you came up with that you were proud of?”
• Share students' story problems.

The purpose of this activity is for students to create a poster of their story problem so that others can solve it. Students use these posters in the next activity, in which they solve, and write equations for other students’ story problems. They notice connections between the equation and the written problem and create a poster that communicates their work.

Alternatively, to make this task more challenging, students can rewrite their stories as missing addend story problems.

• Groups of 2
• Give each group tools for creating a visual display.
• “Ahora vamos a usar sus problemas-historia de la actividad anterior para hacer pósteres. El objetivo es mostrar cómo pensamos y retarnos mutuamente” // “Now we’re going to use your story problems from the last activity to make posters so we can show our thinking and challenge each other.”

• “Escojan un problema-historia que ustedes o su compañero escribieron. Hagan un póster con ese problema-historia. Sus compañeros de clase lo van a resolver en la siguiente actividad, así que asegúrense de no incluir la respuesta” // “Choose one of the story problems you and your partner wrote. Create a poster with your story problem. Your classmates will solve it in the next activity. So make sure to not include the answer.”
• 5 minutes: partner work time.
• “Tomen turnos para compartir su póster con otra pareja de su mesa” // “Take turns sharing your poster with another pair at your table.”
• “La pareja que escucha debe decirle a los presentadores si su póster es claro y organizado” // “The pair listening should tell the presenters if their poster is clear and organized.”
• 5 minutes: group work time.
• If needed, give students an opportunity to revise their posters.

• “¿Qué cosas le cambiaron a su póster para hacerlo claro y organizado para el recorrido por el salón?” // “What were some things you changed to make your poster clear and organized for the gallery walk?” (We wrote the story problem bigger. We added a picture to go with my story.)

The purpose of this activity is for students to solve their classmates’ story problems. Students may use any method that makes sense to them to solve the addition and subtraction story problems.

• Groups of 2
• Give students access to double 10-frames and connecting cubes or two-color counters.
• Set up posters in an accessible way for all students.

• “Recorran el salón y lean los problemas-historia de sus compañeros. Luego, resuelvan los problemas y escriban ecuaciones para cada uno” // “You will go around the room and read your classmates’ story problems. Then solve and write equations for them.”
• 8 minutes: gallery walk

• “Reflexionemos sobre el trabajo que hicimos hoy” // “Let’s reflect on the work we did today.”