Lesson 15

This warm-up prompts students to carefully analyze and compare expressions and equations. 

• Groups of 2
• Display the image.
• “Escojan una que sea diferente. Prepárense para compartir por qué es diferente” // “Pick one that doesn’t belong. Be ready to share why it doesn’t belong.”
• 1 minute: quiet think time

• “Discutan con su compañero cómo pensaron” // “Discuss your thinking with your partner.”
• 2–3 minutes: partner discussion
• Share and record responses.

• “Encontremos al menos una razón por la que cada una es diferente” // “Let’s find at least one reason why each one doesn’t belong.”

The purpose of this activity is for students to fluently add and subtract within 5. Students look at the expression on their card and move quickly to the corner that is labeled with the correct answer. There are 16 expression cards included in the blackline master.

• Each student needs one card from the Expression Cards set used in a previous lesson. 
• Label each corner of the classroom with a large number: 2, 3, 4, and 5.

• Give each student an expression card.
• “Encuentren el valor de la expresión que está en su tarjeta. Vayan a la esquina que está marcada con el valor de la expresión” // “Find the value of the expression on your card. Go to the corner that is labeled with the value of the expression.”

• 30 seconds: independent work time
• “Busquen un compañero en su esquina. Muéstrenle su tarjeta y díganle cómo encontraron el valor de su expresión” // “Find a partner in your corner. Show them your card and tell them how you found the value of your expression.”
• 2 minutes: partner discussion
• “Regresen al centro del salón. Intercambien su tarjeta con un compañero” // “Walk back to the center of the room. Trade your card with a partner.”
• Repeat the steps above 3–4 times, as time allows.

• Display the expression \(3 - 1\).
• “Noah vio esta expresión y fue a la esquina que estaba marcada con un 4. ¿Lo hizo bien? ¿Cómo lo saben?” // “Noah saw this expression and went to the corner labeled 4. Was he correct? How do you know?” (No, because this is 3 take away 1 and that is 2.)
• “¿Por qué piensan que él fue a la esquina que estaba marcada con un 4?” // “Why do you think he went to the corner labeled 4?” (He might have thought it was \(3 + 1\) instead of \(3 - 1\).)

The purpose of this activity is for students to compare the total or difference of expressions. Students may add or subtract to find the value or they may decide which expression is greater based on reasoning about operations or the number sequence (MP7). For example, students know that \(4 + 1\) is greater than \(4 - 3\) because one is adding to 4 and the other is taking away. As a variation, the student whose card has an expression with a lesser value takes both cards.

• Each group of 2 needs a set of Expression Cards from a previous lesson.

• Groups of 2
• Give each group of students a set expression cards.
• Invite each student to make a pile with half of the cards.
• Ustedes y su compañero van a voltear cada uno una tarjeta. Miren ambas expresiones. Si su expresión muestra el número que es más, digan ‘¡Yo!’ y luego explíquenle a su compañero cómo lo saben. Si ambas expresiones muestran el mismo número, digan ‘¡El mismo!’” // “You and your partner will both flip over a card. Look at both expressions. If your expression shows the number that is more, say ‘Me!’ and then explain to your partner how you know. If both expressions show the same number, say ‘Same!’”
• Display two expression cards: \(2 + 0\) and \(4 + 1\).
• “¿Cuál expresión muestra un número que es más?” // “Which expression shows a number that is more?” (\(4 + 1\) is more than \(2 + 0\). I know that because 4 and 1 more is 5, which is more than 2.)

• “Jueguen por turnos con su compañero hasta que se les acaben las tarjetas” // “Take turns playing with your partner until you run out of cards.”
• 8 minutes: partner work time

• Display cards with \(4 - 2\) and \(2 + 0\).
• “Cuéntenle algo a su compañero sobre estas expresiones usando las palabras ‘menos’ o ‘el mismo número que’” // “Tell your partner about these expressions using ‘less’ or ‘the same number as.’” (\(4 -2\) is the same number as \(2 + 0\). They are both 2.)

The purpose of this activity is for students to choose from activities that offer practice with number and shape concepts. Students choose from 5 centers introduced in previous units. Students can choose to work at any stage of the centers.

• 5-frames
• Roll and Add
• Bingo
• Geoblocks
• Find the Value of Expressions

Students will continue to choose from these centers in upcoming lessons. Keep the materials from each center organized to use each day.

• Gather materials from: 
  • 5-frames
  • Roll and Add
  • Bingo
  • Geoblocks
  • Find the Value of Expressions

• 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

• Invite students to work at the center of their choice.
• 10 minutes: center work time

• “Cuéntenle a su compañero sobre alguna vez en la que hayan usado una herramienta matemática como ayuda en los centros. ¿Cómo les ayudó la herramienta?” // “Tell your partner about a time when you used a math tool to help you during centers. How did the tool help you?”