Lesson 2

This warm-up prompts students to carefully analyze and compare the features of four partitioned shapes. It allows the teacher to hear the terminologies students use to talk about fractions and fractional parts. In making comparisons, students have a reason to use language precisely (MP6).

• Groups of 2
• Display the image.
• “Escojan uno 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 pareja cómo pensaron” // “Discuss your thinking with your partner.”
• 2–3 minutes: partner discussion
• Share and record responses.

• “¿Qué representa la parte sombreada de la figura D?” // “What does the shaded part in D represent?” (\(\frac{1}{3}\) or one-third of the shape).
• Shade one part of B and C.
• “¿Cada parte sombreada es también un tercio de la figura?” // “Is each shaded part one-third of the shape as well?” (Yes for B, no for C.)
• “¿Por qué en C la parte sombreada no es un tercio del cuadrado?” // “Why is the shaded part not one-third of the square in C?” (The parts aren’t equal in size.)
• Shade one part of A. “¿Esta parte es un tercio del cuadrado?” // “Is it a third of the square?” (No, it is \(\frac{1}{4}\) or one-fourth.)

The purpose of this activity is to activate what students know about the meaning and size of non-unit fractions. Students match a set of fractions with diagrams that represent them. There are a 3 sets of equivalent fractions to prompt students to share what they know about equivalent fractions.

To add movement to the activity, students can check their matches with other groups in the room before the synthesis.

• Groups of 2
• Give each student a straightedge
• Record and display the fraction \(\frac{1}{4}\). 
• “Descríbanle a su pareja cómo se vería el diagrama para esta fracción” // “Describe to your partner what the diagram would look like for this fraction.”
• 30 seconds: partner discussion
• Record and display the fraction \(\frac{2}{4}\).
• “Describan cómo se vería el diagrama para esta fracción” // “Describe what the diagram would look like for this fraction.” 
• 30 seconds: partner discussion
• Share responses. 
• “En una lección anterior, estudiamos fracciones que tenían 1 en el numerador. Ahora vamos a ver fracciones con otros números en el numerador” // “In an earlier lesson, we looked at fractions with 1 for the numerator. Now let’s look at fractions with other numbers for the numerator.” 
• As a class, read aloud the word name of each fraction in the task.

• “En silencio, piensen durante un minuto en cómo podrían emparejar cada fracción con un diagrama que la represente” // “Take a minute to think quietly about how you might match each fraction with a diagram that represents it.”
• 1 minute: quiet think time
• “Con un compañero, emparejen cada fracción con un diagrama. Dos de las fracciones no tienen un diagrama correspondiente. Usen los diagramas en blanco para representarlas” // “Work with a partner to match each fraction with a diagram. Two of the fractions have no matching diagrams. Use the blank diagrams to create representations for them.”
• 10 minutes: group work time

• Invite students to share how they went about making the matches. 
• Highlight explanations that emphasize the meaning of numerator and denominator in a fraction.
• Ask students if they noticed that some diagrams have the same amount shaded but the fractions they represent have different numbers. “¿Cuáles diagramas muestran esto?” // “Which diagrams show this?” (A and L, B and H, C and E, I and K)
• “¿Qué significa que los diagramas que representan esas fracciones sean los mismos?” // “What does it mean that the diagrams representing those fractions are the same?” (The fractions are the same size. The term “equivalent” may or may not come up at this point.)

This activity extends students’ reasoning about the meaning of numerator and denominator and the size of non-unit fractions to include fractions greater than 1. Students see the size of 1 whole marked in a couple of diagrams and learn that the same size applies to all diagrams. They are prompted to both interpret diagrams and create them: they write a fraction to represent the shaded part of a diagram and partition a diagram to represent a given fraction.

Some students may benefit from having physical manipulatives to help them conceptualize fractions that are greater than 1. Consider using fraction strips to support them, for instance, by asking them to fold as many strips as needed to represent, say, 4 halves or 5 fourths.

• Each student needs access to their fraction strips from a previous lesson. 

• Groups of 2
• Give each student a straightedge and access to their fraction strips from a previous lesson.
• “¿De qué manera pueden mostrar \(\frac{3}{4}\) con tiras de fracciones?” // “How can you show \(\frac{3}{4}\) with fraction strips?” (Find the strip showing fourths, highlight 3 parts of fourths.)
• “¿De qué manera pueden mostrar \(\frac{8}{4}\)?” // “How can you show \(\frac{8}{4}\)?” 
• 1 minute: partner discussion
• If students say that they don’t have enough strips to show 8 fourths, ask them to combine their strips with another group's.
• Invite groups to share their representations of \(\frac{8}{4}\). Students may use different fractional parts (fourths and halves, or fourths and eighths).
• Display two strips that show fourths side by side, as shown.
  

  

  

• Count the fourths: “\(\frac{1}{4}\), \(\frac{2}{4}\), . . . , \(\frac{8}{4}\).”
• “¿Cuántos cuartos contamos?” // “How many fourths did we count?” (8) “¿Cuántas unidades son?” // “How many wholes was that?” (2)

• “Cada corchete del primer diagrama muestra 1 unidad. El tamaño de 1 unidad es el mismo en todos los diagramas” // “Each bracket in the first diagram shows 1 whole. The size of 1 whole is the same in all the diagrams.”
• “Trabajen un momento en la primera pregunta. Después, discutan sus respuestas con su pareja” // “Take a moment to work on the first question. Then, discuss your responses with your partner.”
• “Prepárense para explicar cómo saben cuál fracción representa cada diagrama” // “Be prepared to explain how you know what fractions the diagrams represent.”
• 2–3 minutes: independent work time on the first question
• 2 minutes: partner discussion
• Pause for a discussion.
• “¿Cómo decidieron qué fracciones representan los diagramas?” // “How did you determine what fractions the diagrams represent?” (Count the number of parts in 1, and then count the number of shaded parts.)
• Display students’ work, or display and annotate the tape diagrams as they explain.
• Consider labeling each part with the unit fraction and counting each shaded part aloud (“1 medio, 2 medios, 3 medios” // “1 half, 2 halves, 3 halves,” or “1 tercio, 2 tercios, 3 tercios, 4 tercios” // “1 third, 2 thirds, 3 thirds, 4 thirds”) before writing the represented fractions (\(\frac{3}{2}\) or \(\frac{4}{3}\)).
• “Trabajen en la segunda pregunta con su pareja. Pueden usar una regla como ayuda para dibujar sus diagramas” // “Work with your partner on the second question. You may use a straightedge to help you draw your diagrams.”
• 5–7 minutes: partner work time

Students may not attend to the size of 1 whole as they partition the blank diagrams. Consider asking: “¿Qué representa cada parte en tu diagrama? ¿Cómo lo sabes?” // “What does each part in your diagram represent? How do you know?” and “¿Dónde ves 1 unidad en tu diagrama?” // “Where is 1 whole in your diagram?”

• Select students to share their completed diagrams.
• “¿Cómo supieron en cuántas partes debían partir cada diagrama y cuántas partes debían colorear?” // “How did you know how many parts to partition each diagram and how many parts to shade?“ (Cut each 1 whole portion into as many equal parts as the number in the denominator. Shade as many parts as the number in the numerator.)
• “¿Cómo partieron un diagrama en 4 partes iguales?” // “How did you partition a diagram into 4 equal parts?” (Split each 1 whole into 2, and then split each half into 2 parts again.)
• “¿Cómo partieron un diagrama en 8 partes iguales?” // “How did you partition a diagram into 8 equal parts?” (Split each fourth into 2 parts.)