Lesson 10

Escribamos números de dos dígitos

Warm-up: Observa y pregúntate: Mismo dígito, posición diferente (10 minutes)

Narrative

The purpose of this activity is for students to see the connection between base-ten diagrams and written numbers. In the synthesis, students consider the relationship between numbers with the same digit in different places. Students also observe that the single-digit number has no tens.

Launch

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

Activity

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

Student Facing

¿Qué observas?
¿Qué te preguntas?

7

70

17

71

Activity Synthesis

• “¿En qué se parecen y en qué son diferentes 7 y 17?” // “How are 7 and 17 the same and different?” (They both use the digit 7 but only 17 has 1 ten. Seven has no tens.)
• “¿En qué se parecen y en qué son diferentes 7 y 70?” // “How are 7 and 70 the same and different?” (7 is a one-digit number and 70 is a two-digit number. They both have a 7 as a digit. 70 has 7 tens. 7 has 7 ones.)
• “¿En qué se parecen y en qué son diferentes 70 y 71?” // “How are 70 and 71 the same and different?” (Both have 7 tens, but 71 has 1 one instead of 0 ones.)

Activity 1: Escribamos números que correspondan a representaciones en base diez (15 minutes)

Narrative

The purpose of this activity is for students to produce written numbers for a given quantity represented in different ways. Some representations show the tens on the left and others show the ones on the left. Students must attend to the units in each representation and the meaning of the digits in a two-digit number, rather than always writing the number they see on the left in a representation in the tens place and the number they see on the right in a representation in the ones place (MP6).

Engagement: Develop Effort and Persistence. Chunk this task into more manageable parts. Check in with students to provide feedback and encouragement after each chunk.
Supports accessibility for: Attention, Social-Emotional Functioning

Launch

• Groups of 2
• Give students access to connecting cubes in towers of 10 and singles.

Activity

• “Empiecen a trabajar solos. Cuando ustedes y sus parejas hayan terminado, comparen lo que hicieron” // “You will work on your own to start. When you and your partner are finished, compare your work.”
• 5 minutes: independent think time
• 3 minutes: partner discussion

Student Facing

Escribe el número que corresponda a cada representación.

Número: ____________

2.

Número: ____________

3. 9 decenas

Número: ____________

4. $$20 + 5$$

Número: ____________

5.

Número: ____________

6. $$7 + 40$$

Número: ____________

Número: ____________

8.

Número: ____________

9. $$1 + 40$$

Número: ____________

10.

Número: ____________

Activity Synthesis

• Invite students to share the two-digit number that matches each representation and explain how it matches.

Activity 2: Conozcamos “Escribe números: Números hasta el 99 de 1 en 1” (20 minutes)

Narrative

The purpose of this activity is for students to learn a new center called Write Numbers. Students write a two-digit number in each space on a gameboard. They take turns writing the next one, two, or three numbers in the sequence. The player who writes the last number on the board wins. Students may choose to count forward or backward.

MLR8 Discussion Supports. Synthesis: Provide students with the opportunity to rehearse with a partner what they will say about the patterns they saw before they share with the whole class.

Required Materials

Materials to Gather

Materials to Copy

• Write the Number Stage 1 Gameboard, Spanish

Required Preparation

• Put each gameboard in a sheet protector.

Launch

• Groups of 2
• Give each group a gameboard and a dry erase marker.
• “Vamos a conocer un centro nuevo llamado ‘Escribe números’” // “We are going to learn a new center called Write Numbers.”
• Display the gameboard.
• “Ustedes y sus parejas van a practicar la escritura de números. Van a completar el camino de los números en el tablero de juego. Pueden decidir empezar con el número más pequeño y contar hacia adelante o empezar con el número más grande y contar hacia atrás. En cada turno, pueden decidir si les gustaría escribir uno, dos o tres números en el tablero. Gana la persona que escriba el último número en el tablero” // “You and your partner will practice writing numbers. You will fill in the number path on the gameboard. You can decide to start with the smaller number and count forward, or start with the larger number and count backward. On each turn, you can decide whether you would like to write one, two, or three numbers on the gameboard. The person who writes the last number on the board is the winner.”
• Demonstrate playing one round with the students.
• “Ahora van a jugar con su pareja” // “Now you will play with your partner.”

Activity

• 10 minutes: partner work time

Activity Synthesis

• “¿Qué patrones vieron mientras escribían los números?” // “What patterns did you see as you wrote numbers?” (The ones place goes up by one each time until you get to 9. Then the tens place changes by one, and the 0–9 pattern repeats.)

Lesson Synthesis

Lesson Synthesis

Display 702.
“Hoy escribimos números de dos dígitos. Clare contó una colección de setenta y dos objetos. Este es el número que escribió. Muestren un pulgar arriba si están de acuerdo y un pulgar abajo si están en desacuerdo” // “Today we wrote two-digit numbers. Clare counted a collection of seventy-two objects. This is the number she wrote. Give a thumbs up if you agree and a thumbs down if you disagree.”
“¿Qué consejo le darían a Clare para escribir números que tienen decenas y unidades?” // “What advice do you have for Clare about writing numbers that have tens and ones?” (When writing tens and ones there are only 2 digits. The first digit tells the number of tens and the second digit tells the number of ones. There is no 0 in 72, even if it sounds like there should be.)