Lesson 16

The purpose of this Number Talk is to elicit strategies and understandings students have for subtracting within 10. These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to add and subtract numbers within 10. 

• Display one expression.
• “Hagan una señal cuando tengan una respuesta y puedan explicar cómo la obtuvieron” // “Give me a signal when you have an answer and can explain how you got it.”
• 1 minute: quiet think time

• Record answers and strategy.
• Keep expressions and work displayed.
• Repeat with each expression. 

• “¿Cómo les puede ayudar la primera ecuación a resolver la segunda?” // “How can the first equation help you with the second equation?” (If I know that 9 – 7 is 2, then I know that 9 – 2 is 7.)
• “¿Cómo les puede ayudar la tercera ecuación a resolver la cuarta?” // “How can the third equation help you with the fourth equation?” (If I know that 8 – 6 is 2, then I know that 8 – 2 is 6.)
• “¿Alguien puede expresar el razonamiento de _____ de otra forma?” // “Who can restate _____'s reasoning in a different way?”

The purpose of this activity is for students to learn Stage 2 in the Capture Squares center. In this stage, students choose two number cards and find the difference using math tools or mental methods they have developed during the unit. They connect two dots that are adjacent to the number. If that line closes the square, they capture it and shade it in their color. The player to shade in three squares first is the winner. 

• Groups of 2
• Give each group a set of number cards, two different colored crayons or colored pencils, a game board, and access to connecting cubes or two-color counters. 
• “Vamos a aprender una nueva forma de jugar el centro 'Captura cuadrados'. Juguemos una ronda juntos” // “We are going to learn a new way to play Capture Squares. Let’s play a round together.”
• Choose two number cards.
• “Hoy vamos a restar los números en vez de sumarlos. ¿Cuál es la diferencia entre estos números? ¿Cómo lo saben?” // “Today we are going to subtract the numbers instead of adding them. What is the difference between these numbers? How do you know?”
• 1 minute: quiet think time
• 30 seconds: partner discussion
• Share responses.
• “Ahora yo encuentro el cuadrado que muestra la diferencia. Dibujo una línea que conecte dos puntos en ese cuadrado” // “Now I find the square that shows the difference. I draw a line connecting two dots on that square.”
• Repeat 1–2 more times, as needed.
• “Cuando dibujo la línea que completa el cuadrado, coloreo ese cuadrado con mi color. Gana la primera persona que coloree tres cuadrados” // “If I draw the line that completes the square, I shade in that square my color. The first person to shade in three squares, wins."

• 12 minutes: partner work time

• Display a game board with a couple of squares shaded. Draw three lines around the 3 so one more is needed to fill in the square.
• “¿Cuáles tarjetas de números podría escoger para capturar el cuadrado que tiene el 3?” // “What number cards could I pick that would allow me to capture the square with the 3?” (10 and 7, 9 and 6, 8 and 5, 7 and 4, 6 and 3, 5 and 2, 4, and 1)

The purpose of this activity is for students to choose from activities that focus on addition and subtraction within 10. Students choose from any stage of previously introduced centers.

• Math Stories
• Shake and Spill
• What’s Behind My Back

• Gather materials from previous centers:
  • Math Stories, Stage 4
  • Shake and Spill, Stage 3 and 4
  • What's Behind My Back, Stage 2

• Groups of 2
• “Ahora van a escoger centros de los que ya conocemos” // “Now you 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. 
• 15 minutes: center work time

• “Digan una cosa que hayan aprendido o en la que hayan mejorado al trabajar en las actividades que escogieron” // “What is one thing you learned or got better at by working on the activities you chose?”