Lesson 21

The purpose of this What Do You Know About _____? is to invite students to share what they know and how they can represent the number 20.

• Display the number 20.
• “¿Qué saben sobre 20?” // “What do you know about 20?”
• 1 minute: quiet think time

• Record responses.

• “¿Qué conexiones ven entre las diferentes respuestas?” // “What connections do you see between different answers?”
• Pick two addition expressions that use different addends and ask, “¿Cómo se relacionan estas dos expresiones?” // “How are these two expressions related?”

The purpose of this lesson is for students to learn stage 1 of the center, How Close? Students pick a given number of digit cards and then choose a subset of those to make an expression that yields a number as close as possible to 20.

• Groups of 2
• Give each group a set of number cards, two recording sheets, and access to double 10-frames and connecting cubes or two-color counters.
• “Vamos a aprender un juego llamado ‘¿Qué tan cerca?: Suma para obtener 20’. Juguemos la primera ronda juntos” // “We are going to learn a game called How Close? Add to 20. Let's play the first round together.”
• “Primero saquemos todas las tarjetas que tengan el número 10. No vamos a usar esas tarjetas en este juego” //  “First we take out any card that has the number 10. We will not use those cards for the game.”
• Display 5 cards.
• “Puedo escoger dos o tres de estas tarjetas para sumar y acercarme a 20 lo que más pueda. ¿Qué tarjetas debería escoger?” // “I can choose two or three of these cards to add to get as close to 20 as I can. What cards should I choose?”
• 1 minute: quiet think time
• 2 minutes: partner discussion
• Share responses.
• “Escribo una ecuación que tenga los números que escogí y la suma de los números” // “I write an equation with the numbers I chose and the sum of the numbers.”
• Demonstrate writing the equation on the recording sheet.
• “La persona que obtenga la suma más cercana a 20 gana un punto en esa ronda. Después, toman más tarjetas. Cada uno debe tener siempre cinco tarjetas para escoger. Jueguen otra vez. Gana la persona que obtenga más puntos” // “The person who gets a sum closer to 20 gets a point for the round. Then you each get more cards so you always have five cards to choose from. Play again. The person who gets more points wins.”

• 10 minutes: partner work time

• Invite students to share their methods for making a sum close to 20. 

The purpose of this activity is for students to learn stage 3 of the Five in a Row center. Students choose to add 7, 8, or 9 to the number on their card and then place their counter on the sum on the gameboard. The first partner to have five counters in a row wins.

• Groups of 2
• “Vamos a aprender una nueva forma de jugar ‘Cinco en línea’” // “We are going to learn a new way to play Five in a Row.”
• Display the gameboard and pick a number card.
• “Puedo escoger si le sumo 7, 8 o 9 al número que está en esta tarjeta. ¿Cuál debería sumar?” // “I can decide to add 7, 8, or 9 to the number on this card. What should I add?”
• 30 seconds: quiet think time
• 1 minute: partner discussion
• Share responses.
• Choose 7, 8, or 9 to add to the number and find the sum.
• “Ahora pongo una ficha donde está la suma en el tablero. Después, es el turno de mi compañero. Sigan jugando hasta que alguien complete cinco fichas en línea” // “Now I put a counter on the sum on the gameboard. Then it is my partner's turn. Continue playing until someone gets five counters in a row.”

• 10 minutes: partner work time

• “¿Qué método vieron que su compañero usó para decidir si sumar 7, 8 o 9?” // “What method did you see your partner use to decide whether to add 7, 8, or 9?”