Lesson 8

The purpose of this Choral Count is to invite students to practice counting by 1 from 80 to 110 to prepare them to count large groups of objects later in the lesson. Students will develop an understanding of three-digit numbers and a hundred as a unit in grade 2. 

• “Contemos desde 80 hasta 110” // “Let’s count from 80 to 110.”
• Record as students count.
• Stop counting and recording at 110.

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

• “¿Qué observan sobre este conteo grupal?” // “What do you notice about this choral count?” (When we get to 100, there are 3 digits. Counting starts all over again at 1, but now it’s with 100.)

The purpose of this activity is to measure a length that is over 100 length units long and count the number of units using grouping methods. Some students may count by 1, others may organize their cubes into groups of 10. Although some students may attempt to represent their counts with a written number, the emphasis is representing the length of the string with a drawing. Students will identify written numbers in the next activity and practice writing them in the next lesson.

When students look for efficient ways to count the cubes, such as grouping them by tens, they look for and make use of base-ten structure (MP7).

• Each group needs 120 base-ten cubes.

• Groups of 3–4
• Give each group 120 base-ten cubes, string, and scissors.
• “Hoy van a escoger a un compañero de su grupo y van a medir su estatura. Corten un pedazo de cuerda que sea de la misma longitud que la estatura de su compañero” // “Today we are going to measure the height of one of your group members. Choose whose height you will measure and cut a piece of string that is the same length as their height.”
• 2 minutes: small-group work

• “Midan la longitud de la cuerda usando cubos pequeños. Representen la medida con dibujos, números o palabras” // “Measure the length of the string using small cubes. Represent the measurement using drawings, numbers, or words.”
• 15 minutes: partner work time
• Monitor for groups who:
  • have measurements between 100–110 cubes
  • created groups of ten to organize the cubes

If students try to draw each cube in a straight line to represent their count and begin to run out of space, consider asking:

• “¿Cómo planeas representar tu medida?” // “How are you planning to represent your measurement?”
• “¿En qué se parece esta actividad a contar colecciones? ¿Cómo representas lo que cuentas cuando es una colección grande?” // “How was this activity like counting collections? How do you represent your count when it's a large collection?”

• Invite previously identified students to share.
• “¿Cómo contaron los cubos?” // “How did you count the cubes?” (We organized them into groups of 10. When we couldn’t make any more groups of 10 we left the singles. Then we counted the groups by 10 and counted the singles last.)

The purpose of this activity is for students to match representations of tens and ones to written numbers up to 100. Students may count by tens and ones. Some students may see that 10 tens can be grouped to make 100. After they count, they match the written number to the picture.

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

• Groups of 2
• Give each group a set of cards.
• Display the student workbook page.
• “Esta es la cantidad de cubos que se necesitaron para medir la estatura de Jada. ¿Qué observan acerca de esta representación?” // “This is how many cubes it took to measure Jada’s height. What do you notice about this representation?” (There are groups of ten and singles. There are 10 groups of 10 and 4 singles. There are 104 cubes.)
• “La estatura de Jada es 104 cubos pequeños. Así escribimos 104” // “Jada’s height is 104 small cubes. This is how we write 104.”
• Display the numeral 104.

• “Van a observar más representaciones de cubos que se usaron para medir la estatura de algunos estudiantes. Emparejen cada imagen con el número que la representa” // ‘You are going to look at more representations of cubes used to measure students’ height. Match each picture to the number that represents it.”
• 8 minutes: partner work time

• Display all cards that show 100 or more.
• “¿Qué observan acerca de estas representaciones?” // “What do you notice about these representations?” (They all have 10 tens. There are more than 100 cubes.)