Lesson 3
Contemos para sumar y restar
Warm-up: Conteo grupal: Hacia adelante y hacia atrás (10 minutes)
Narrative
Launch
- “Contemos hasta 20” // “Let’s count to 20.”
- Record as students count.
- “Esta vez, en lugar de empezar en 1 y contar hacia adelante, vamos a empezar en 10 y a contar hacia atrás hasta que lleguemos a 1. Empecemos en 10 y contemos hacia atrás hasta 1” // “This time, instead of starting a 1 and counting forward, we are going to start at 10 and count backward until we get to 1. Let’s start at 10 and count backward to 1.”
Activity
- Repeat 3–4 times.
- “Empecemos en 20 y contemos hacia atrás hasta 1” // “Let’s start at 20 and count backward to 1.”
- Repeat 2–3 times.
Student Response
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Activity Synthesis
- “En la lección de hoy, vamos a resolver problemas-historia en los que contar hacia adelante o hacia atrás les puede ayudar” // “In today’s lesson we will solve story problems where counting forward and backward may help you.”
Activity 1: Viajar en bus (10 minutes)
Narrative
The purpose of this activity is for students to use their knowledge of the count sequence to solve Add To, Result Unknown and Take From, Result Unknown story problems where one is added or taken away.
Advances: Speaking, Representing
Required Materials
Materials to Gather
Launch
- Groups of 2
- Give students access to connecting cubes and 10-frames.
- “Hoy van a resolver dos problemas-historia sobre personas que viajan en un bus” // “Today you are going to solve two story problems about people on a bus.”
Activity
- Read the first story problem.
- “Cuéntenle a su pareja lo que sucedió en la historia” // “Tell your partner what happened in the story.”
- 30 seconds: quiet think time
- 1 minute: partner discussion
- Monitor for students who accurately retell the story. Choose at least one student to share with the class.
- Reread the task statement.
- “Muestren cómo pensaron. Usen dibujos, números, palabras u objetos” // “Show your thinking using drawings, numbers, words, or objects.”
- 2 minutes: quiet work time
- 2 minutes: partner discussion
- Repeat the steps with the second story problem.
- Monitor for a student who can explain how they just knew the answer without making a representation.
Student Facing
-
Había 7 personas en el bus.
Después, 1 persona más subió al bus.
¿Cuántas personas hay ahora en el bus?Muestra cómo pensaste. Usa objetos, dibujos, números o palabras.
_______________
-
Había 10 personas en el bus.
Después, 1 persona bajó del bus.
¿Cuántas personas hay ahora en el bus?Muestra cómo pensaste. Usa objetos, dibujos, números o palabras.
_______________
Student Response
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Activity Synthesis
- Invite a previously identified student to share how they solved the second story problem.
Activity 2: Estudiantes que cantan (15 minutes)
Narrative
The purpose of this activity is for students to complete and solve numberless Add To, Result Unknown and Take From, Result Unknown story problems. The story problems are about adding and subtracting 1, but they do not give a starting number and therefore highlight that adding 1 to any number gives the next number in the count sequence while subtracting 1 from any number gives the previous number in the count sequence. While the kindergarten standards only ask students to solve story problems with a result of up to 10, students may choose larger numbers for their problems.
Students may benefit from having the story problems in this activity read aloud multiple times.
Supports accessibility for: Conceptual Processing, Organization
Required Materials
Materials to Gather
Launch
- Give students access to connecting cubes and 10-frames.
- “Algunos estudiantes estaban cantando. Después, vino 1 estudiante más a cantar con ellos. ¿Cuántos estudiantes están cantando ahora?” // “Some students were singing. Then 1 more student came to sing with them. How many students are singing now?”
- “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?” (Students were singing. Another student came to sing. How many students were singing? How many students are singing now?)
- 30 seconds: quiet think time
- 1 minute: partner discussion
- Share and record responses.
Activity
- “Al problema-historia le hace falta el primer número. Llenen el espacio en blanco con un número y cuéntenle el problema-historia a su pareja. Muestren cómo pensaron. Usen objetos, dibujos, números o palabras” // “The story problem is missing the first number. Fill in a number and tell the story problem to your partner. Show your thinking using objects, drawings, numbers, or words.”
- 4 minutes: partner work time
- Repeat the steps, including noticing and wondering, with the second story problem.
Student Facing
-
__________ estudiantes estaban cantando.
Después, vino 1 estudiante más a cantar con ellos.
¿Cuántos estudiantes están cantando ahora?Muestra cómo pensaste. Usa objetos, dibujos, números o palabras.
_______________
-
__________ estudiantes estaban cantando.
Después, 1 estudiante dejó de cantar y se fue a su casa.
¿Cuántos estudiantes están cantando ahora?Muestra cómo pensaste. Usa objetos, dibujos, números o palabras.
_______________
Student Response
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Activity Synthesis
- Invite a student to share a story for the first problem. (There were 8 students singing. Then 1 more student came to sing with them. How many students are singing now?)
- “¿Cuántos estudiantes están cantando ahora? ¿Cómo lo saben?” // “How many students are singing now? How do you know?” (9 because 9 is 1 more than 8. 9 comes after 8 when we count.)
- “¿Y si había 9 estudiantes cantando y vino 1 más a cantar con ellos? ¿Cuántos estudiantes están cantando ahora? ¿Cómo lo saben?” // “What if there were 9 students singing and 1 more came to sing with them? How many students are singing now? How do you know?” (10. 10 is 1 more than 9.)
Activity 3: Centros: Momento de escoger (15 minutes)
Narrative
- Less, Same, More
- Math Fingers
- Tower Build
- Math Stories
- Which One
Required Materials
Materials to Gather
Required Preparation
- Gather materials from:
- Less, Same, More
- Math Fingers
- Tower Build
- Math Stories
- Which One
Launch
- Groups of 2
- “Hoy vamos a escoger centros de los que ya conocemos” // “Today we 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
Activity
- Invite students to work at the center of their choice.
- 10 minutes: center work time
Student Facing
Escoge un centro.
Menos, lo mismo, más
Dedos matemáticos
Construcción de torres
Historias matemáticas
¿Cuál es?
Activity Synthesis
- “¿Qué pueden hacer cuando hay un problema de matemáticas o un centro sobre el que no están seguros?” // “What can you do when there is a math problem or center that you’re not sure about?”
Lesson Synthesis
Lesson Synthesis
“Hoy trabajamos con problemas-historia en los que una cosa se suma o en los que una cosa se resta, o se quita” // “Today we worked with story problems where one thing is added or one thing is subtracted, or taken away.”
“Cuando le suman 1 a un número, ¿qué número obtienen?” // “When you add 1 to a number, which number do you get?” (The next number when we count, the number that is one more)
“¿Alguien puede compartir un ejemplo de cuándo hicieron eso hoy?” // “Can someone share an example of when they did that today?”
“Cuando le quitan 1 a un número, ¿qué número obtienen?” // “When you take away 1 from a number, which number do you get?” (The one before the number when we count, the number that is one less, the number you say when you count backward)
Cool-down: Bajar del bus (5 minutes)
Cool-Down
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