Lesson 21

The purpose of this warm-up is to allow students to connect language to mathematical representation, which will be useful when students need to compare quantities and numbers in later activities. In the synthesis, students have the opportunity to practice using the language “less” to compare quantities.

This warm-up gives students opportunities to make sense of a problem by acting it out first before thinking about how to solve the problem (MP1).

• Groups of 2
• Display and read the story.
• “¿De qué se trata la historia?” // “What is the story about?”
• 30 seconds: quiet think time
• Share responses.
• Read the story again.
• “¿Cómo pueden actuar esta historia?” // “How can you act out this story?”
• 30 seconds: quiet think time

• “Discutan con su pareja cómo pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share responses. 
• Choose a way to represent the story as a class.
• Read the story together. 

• “¿Menos estudiantes escogieron leche o agua? ¿Cómo lo saben?” // “Did fewer students choose milk or water? How do you know?” (Fewer students chose water. I know that 5 is less than 9. 5 comes before 9 when we count.)
• “Díganle algo a su pareja sobre los números 9 y 5 usando ‘menos’” // “Tell your partner about the numbers 9 and 5 using ‘less.’”

The purpose of this activity is for students to compare numbers in a way that makes sense to them. Students can use physical objects or make drawings to represent each number (MP5), and match or count to compare. Students can also use their knowledge of the count sequence and understanding that each successive number refers to a quantity that is one more to compare the numbers. In the synthesis students describe how creating representations of numbers helps to compare numbers.

• Groups of 2
• Give students access to connecting cubes or counters.
• “Con su pareja, descubran cuál número es más. Marquen el número que es más” // “Work with your partner to figure out which number is more. Circle the number that is more.”

• 5 minutes: partner work time
• Monitor for students who create representations of the numbers using cubes or a drawing and use these representations to compare.
• Monitor for students who counted to figure out which number is more.

If students circle the number that is less instead of the number that is more, consider asking:

• “¿Qué sabes sobre estos dos números? ¿Qué estás intentando averiguar?” // “What do you know about these two numbers? What are you trying to figure out?“
• “¿Cómo puedes usar los cubos para mostrar cada número? ¿Cómo te pueden ayudar los cubos a descubrir cuál número es más?” // “How can you use the cubes to show each number? How can the cubes help you figure out which number is more?“

• Invite previously selected students to share the representations they made and how they used them to figure out which number is more.
• “¿De qué les sirvió contar objetos separando o hacer dibujos para descifrar cuál número es más?” // “How did counting out the groups of objects or drawing pictures help you figure out which number is more?”
• Invite previously selected students to share how counting helped them compare the numbers.
• “Sabemos que 9 es más que 5. Comparen estos números usando ‘menos’” // “We know 8 is more than 5. Compare these numbers using ‘less’.”

The purpose of this activity is for students to write and compare numbers 1–10. Students compare numbers in any way that makes sense to them.

• Groups of 2
• Give each group a number mat and 2 cubes. Give each group of students access to connecting cubes or counters. 
• “Vamos a lanzar cubos para obtener dos números y a descubrir cuál número es menos” // “We are going to roll two numbers and figure out which number is less.” 
• Invite a student to act as your partner in the demonstration.
• “Primero cada uno lanza un cubo sobre el tablero de números” // “First we each roll a cube onto the number mat.”
• Demonstrate rolling cubes onto the number mat.
• “Después, escribimos ambos números en las líneas” // “Next we write both numbers on the lines.” 
• Demonstrate writing each number on a line. 
• “En la actividad anterior, marcamos el número que es más. Ahora vamos a marcar el número que es menos. ¿Qué podemos hacer para averiguar si 8 es menos o 4 es menos?” // “In the last activity we circled the number that is more. Now we are going to circle the number that is less. What could we do to figure out if 8 or 4 is less?” (You could draw pictures. You could count out objects and compare them. You could think about which number comes first when you count.)
• 30 seconds: quiet think time
• Share responses. 
• Demonstrate one student suggestion for comparing 8 and 4.
• “4 es menos que 8, entonces marcamos el número 4” // “4 is less than 8, so we circle the number 4.”
• “Es su turno de jugar con su pareja. Cada uno lanza un cubo. Después, escriben los números y descifran cuál número es menos” // “It’s your turn to play the game with your partner. You will each roll one cube, write down the numbers, and work together to figure out which number is less.”

• 5 minutes: partner work time

• Display 9 and 2.
• “¿Cuál número es menos? ¿Cómo lo saben?” // “Which number is less? How do you know?” (2. I know that 2 is small. 9 is a lot more. When you count you come to 2 first which means it is less.)

The purpose of this activity is for students to choose activities that offer practice with number and counting concepts

• Less, Same, More
• Math Libs
• Number Race

• Gather materials from:
  • Less, Same, More, Stages 1-4
  • Math Libs, Stage 1
  • Number Race, Stage 1

• “Hoy vamos a escoger centros de los que ya conocemos” // “Today we are going to choose from centers we have already learned.”
• Display the center choices in the student book.
• “Piensen qué les gustaría hacer primero” // “Think about what you would like to do first.”
• 30 seconds: quiet think time

• Invite students to work at the center of their choice. 
• 8 minutes: center work time
• “Escojan qué les gustaría hacer ahora” // “Choose what you would like to do next.”
• 8 minutes: center work time

• Display student pages or materials from centers throughout the units.
• “¿Cuál fue su centro favorito durante esta unidad? ¿Qué hizo que fuera su favorito?” // “What was your favorite center to work on during this unit? What made it your favorite center?”