Lesson 12

The purpose of this warm-up is to elicit the idea that fractions can be used to describe lengths. While students may notice and wonder many things about this statement, the idea that Han and Tyler could have run the same distance or different distances are the important discussion points.

• Groups of 2
• Display the statement.
• “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?”
• 1 minute: quiet think time

• “Discutan con su compañero lo que pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses.

• “¿Cómo pueden las fracciones darnos más información sobre qué distancia corrieron Tyler y Han?” // “How could fractions give us more information about how far Tyler and Han ran?” (Tyler and Han ran \(\frac{1}{2}\) of the field. Tyler ran \(\frac{3}{4}\) of the field and Han ran \(\frac{7}{8}\) of the field.)
• “¿Qué preguntas podemos hacer sobre la situación?” // “What questions could we ask about the situation?” (Did they run the same distance? Who ran farthest? How much farther did one student run than the other?)

The purpose of this activity is for students to explain equivalence using a number line. Students are given situations in a measurement context and have to determine whether the distance is the same. Students are encouraged to use a number line to provide an opportunity to explain fraction equivalence as fractions that are at the same location. They may choose to use two number lines for each question (one for each fraction). Choosing to use one number line or two will be discussed in the synthesis of the next activity. 

When they identify whether or not two fractions of the same trail represent the same distance, students reason abstractly and quantitatively (MP2).

• Groups of 2

• “Decidan con su compañero si los estudiantes de cada pareja corrieron la misma distancia o no. Si les ayuda, pueden usar rectas numéricas para explicar su razonamiento” // “Work with your partner to decide whether each pair of students ran the same distance or not. You can use number lines to explain your reasoning if they’re helpful to you.”
• 5–7 minutes: partner work time
• Monitor for students who use the number lines to explain that the students ran the same distance if the fractions are at the same location on the number line.

• Display a student-created number line that shows \(\frac{1}{4}\) and \(\frac{2}{8}\) at the same location.
• “¿Cómo muestra esto que Jada y Kiran corrieron la misma distancia?” // “How does this show that Jada and Kiran ran the same distance?” (The points that represent them are at the same location between 0 and 1 on the number line.)
• “Aprendimos que dos fracciones son equivalentes si tienen el mismo tamaño. Ahora también sabemos que dos números son equivalentes si están en la misma ubicación en una recta numérica. Como \(\frac{1}{4}\) y \(\frac{2}{8}\) están en la misma ubicación, podemos decir que son equivalentes” // “We’ve learned that two fractions are equivalent if they are the same size. Now we also know that two numbers are equivalent if they are at the same location on a number line. Because \(\frac{1}{4}\) and \(\frac{2}{8}\) are at the same location, we can say they are equivalent.”
• “¿Cómo podemos usar el signo igual para escribir fracciones que son equivalentes?” // “How could we use the equal sign to record fractions that are equivalent?” (\(\frac{3}{6} = \frac{1}{2}\), \(\frac{1}{4} = \frac{2}{8}\))
• Share and record responses.

The purpose of this activity is for students to locate fractions on the number line, and find pairs of fractions that are equivalent. Students can use a separate number line for each denominator, but they can also place fractions with different denominators on the same number line to show equivalence. Focus explanations about why fractions are equivalent on the fact that they share the same location. In the synthesis, discuss how one number line or two can be used to compare fractions.

• Groups of 2

• “Individualmente, ubiquen estos números en la recta numérica. Después, encuentren 4 parejas de fracciones que sean equivalentes. Prepárense para explicar su razonamiento” // “Work independently to locate these numbers on the number line. Then, find 4 pairs of fractions that are equivalent. Be prepared to explain your reasoning.”
• 3–5 minutes: independent work time
• “Ahora compartan con su compañero las parejas de fracciones que escribieron y expliquen cómo saben que son equivalentes” // “Now, share the pairs of fractions you wrote with your partner and explain how you know they are equivalent.”
• 2–3 minutes: partner discussion
• Monitor for students who compare fractions on a single number line and those who compare fractions on separate number lines.

• Select previously identified students to display how a single number line or separate number lines can be used to show equivalent fractions.
• “¿Cuándo tiene sentido usar una sola recta numérica y cuándo ayuda usar dos rectas numéricas?” // “When might it make sense to use a single number line and when might it be helpful to use two number lines?“ (One number line might make sense if one fraction can be partitioned to get to another, like halves to fourths. If a number line is too crowded or has fractions that could be hard to partition together, like halves and thirds, it might be helpful to use two number lines.)

The purpose of this activity is for students to practice generating equivalent fractions. The goal of each round is to use the numbers on the number cubes to complete a statement that shows that two fractions are equivalent. Students roll 6 number cubes and try to use 4 of the numbers to create a statement that shows two equivalent fractions. If students roll a 5 (or a blank), they may choose any number to use. Students may choose to re-roll any of their number cubes up to 2 times. Students get a point for every true statement they make. Students may choose to use fraction strips, diagrams, or number lines to prove that their fractions are equivalent. If students choose to use diagrams, monitor to make sure they are drawing equal-sized wholes.

• Each group of 2 needs 6 number cubes.

• Groups of 2
• Give each group 6 number cubes.
• “Vamos a jugar un juego que se llama ‘Lánzate a hacer fracciones equivalentes’. Leamos las instrucciones y juguemos 1 ronda juntos” // “We’re going to play a game called Rolling for Equivalent Fractions. Let’s read through the directions and play 1 round together.”
• Read through the directions with the class and play a round against the class, displaying the fractions from the cards, drawing tape diagrams, and thinking through decisions aloud.

• “Ahora jueguen con su compañero. Traten de obtener 5 puntos” // “Now, play the game with your partner. See if you can get 5 points.”
• 8–10 minutes: partner work time
• Monitor for students to highlight during the synthesis that:
  • create a diagram of their fraction and generate an equivalent fraction with larger parts, such as picturing \(\frac{2}{8}\) as \(\frac{1}{4}\)
  • create a diagram of the fraction they draw and further partition their fraction to make smaller pieces, such as further partitioning \(\frac{1}{2}\) to make \(\frac{2}{4}\)
  • use a pattern to generate equivalent fractions, such as knowing that there are two sixths in each third, so \(\frac{2}{3}\) is equivalent to \(\frac{4}{6}\)

If students say they aren’t sure what fractions they can make that would be equivalent, consider asking:

• “¿Qué fracciones puedes hacer con lo que sacaste?” // “What fractions could you make with what you rolled?”
• “¿Cómo puedes usar tus tiras de fracciones para decidir si algunas de las fracciones son equivalentes?” // “How could you use your fraction strips to decide if any of the fractions are equivalent?”

• Display number cubes showing 1, 1, 4, 2, 2, 5
• “Si sacaran estos números en su último lanzamiento, ¿qué fracciones equivalentes podrían hacer?” // “If you got these numbers on your last roll, what equivalent fractions could you make?” (\(\frac{2}{4} = \frac{1}{2}\) or \(\frac{1}{4} = \frac{2}{8}\))
• If needed, ask, “¿Qué número debo usar para mi comodín?” // “What number should I use for my wild card?”