Lesson 10

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.

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

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

• “¿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.)

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).

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

• Read the task statement.
• “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

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

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.

• Put each gameboard in a sheet protector.

• 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.”

• 10 minutes: partner work time

• “¿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.)