# Lesson 12

Formas de comparar fracciones

## Warm-up: Exploración de estimación: ¿Cuál es el punto? (10 minutes)

### Narrative

The purpose of this warm-up is for students to practice estimating a reasonable fractional value on a number line. The reasoning here prepares students to use these benchmarks as a way to compare fractions later in the lesson.

The warm-up gives students a low-stakes opportunity to share a mathematical claim and the thinking behind it (MP3).

### Launch

• Groups of 2
• Display the number line.
• “¿Qué estimación sería muy alta?, ¿muy baja?, ¿razonable?” // “What is an estimate that’s too high? Too low? About right?”
• 1 minute: quiet think time

### Activity

• “Discutan con su compañero cómo pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.

### Student Facing

¿Qué valor representa el punto en la recta numérica?

Haz una estimación que sea:

muy baja razonable muy alta
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### Activity Synthesis

• “¿Cómo decidieron qué fracción sería ‘razonable‘?” // “How did you decide what fraction would be ‘about right’?” (The point is a little to the left of the middle point, so the fraction must be a little less than $$\frac{1}{2}$$.)
• “¿Nos ayudaría a hacer mejores estimaciones el escribir la marca ‘1’ como ‘$$\frac{10}{10}$$’ o como ‘$$\frac{100}{100}$$’? ¿Por qué sí o por qué no?” // “Would writing the label ‘1’ as ‘$$\frac{10}{10}$$’ or as ‘$$\frac{100}{100}$$’ help us make better estimates? Why or why not?” (Sample response: It could, because it would help us mentally partition the number line into 10 or 100 parts, which makes it possible to estimate more precisely.)

## Activity 1: La mayor de todas (15 minutes)

### Narrative

In earlier lessons, students compared two fractions that share the same denominator or the same numerator. In this activity, students use that understanding to compare a large set of fractions that are arranged into rows and columns. The fractions in each row share the same numerator and those in each column share the same denominator.

Engagement: Develop Effort and Persistence. Chunk this task into more manageable parts. Invite students to look at column A first, then column B, then row 1. Provide access to pre-made fraction strips for thirds and fifths to help them get started. Check in with students to provide feedback and encouragement after each chunk, particularly in terms of looking for and making use of structure.
Supports accessibility for: Conceptual Processing, Organization, Social-Emotional Functioning

### Launch

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

### Activity

• “Tómense unos minutos en silencio para resolver los problemas. Después, discutan sus respuestas con su pareja” // “Take a few quiet minutes to complete the problems. Afterward, discuss your responses with your partner.”
• 6–7 minutes: independent work time
• “Cuando discutan con su pareja, explíquenle cómo supieron cuál fracción es la mayor de cada fila, de cada columna y de toda la tabla” // “When discussing with your partner, explain how you know which fraction is the greatest in each row, each column, and the entire table.”
• 3–4 minutes: partner discussion

### Student Facing

Esta es una tabla con 25 fracciones.
A B C D E
1 $$\frac{2}{3}$$ $$\frac{2}{5}$$ $$\frac{2}{10}$$ $$\frac{2}{12}$$ $$\frac{2}{100}$$
2 $$\frac{4}{3}$$ $$\frac{4}{5}$$ $$\frac{4}{10}$$ $$\frac{4}{12}$$ $$\frac{4}{100}$$
3 $$\frac{7}{3}$$ $$\frac{7}{5}$$ $$\frac{7}{10}$$ $$\frac{7}{12}$$ $$\frac{7}{100}$$
4 $$\frac{11}{3}$$ $$\frac{11}{5}$$ $$\frac{11}{10}$$ $$\frac{11}{12}$$ $$\frac{11}{100}$$
5 $$\frac{26}{3}$$ $$\frac{26}{5}$$ $$\frac{26}{10}$$ $$\frac{26}{12}$$ $$\frac{26}{100}$$

Prepárate para explicar tu razonamiento en cada pregunta.

1. Identifica la mayor fracción de cada columna (A, B, C, D y E).
2. Identifica la mayor fracción de cada fila (1, 2, 3, 4 y 5).
3. ¿Cuál es la mayor fracción de toda la tabla?

### Student Response

Students may decide $$\frac{26}{3}$$ and $$\frac{26}{5}$$ are less than $$\frac{26}{12}$$ and $$\frac{26}{100}$$ because the former two involve smaller numbers than the latter two. Suggest that students compare fractions with the same numerator, but one that is more familiar (such as those in row 1). Consider asking: “¿Cuál es mayor, $$\frac{2}{5}$$$$\frac{2}{10}$$? ¿ $$\frac{8}{5}$$$$\frac{8}{10}$$?” // “Which is greater, $$\frac{2}{5}$$ or $$\frac{2}{10}$$? $$\frac{8}{5}$$ or $$\frac{8}{10}$$?” Refer them to the diagram of fraction strips to make a similar comparison, if helpful.

### Activity Synthesis

• Invite students to share their responses and reasoning. Highlight responses that clarify that:
• In each column, the fraction in row 5 is the greatest because it has the greatest numerator of all fractions with the same denominator (with fractional parts of the same size).
• In each row, the fraction in column A is greater than others to its right because it has the greatest fractional part of all fractions with the same numerator ($$\frac{1}{3}$$ is greater than $$\frac{1}{5}$$, $$\frac{1}{10}$$, $$\frac{1}{12}$$, and $$\frac{1}{100}$$).
• “¿Cómo supieron que $$\frac{26}{3}$$ es la mayor fracción de toda la tabla?” // “How did you know that $$\frac{26}{3}$$ is the greatest fraction in the entire table?” (Sample responses:
• It is the greatest fraction in row 5 and in column A.
• It is more than 8 wholes. All the other fractions are less than that.)

## Activity 2: Comparar con $\frac{1}{2}$ y 1 (20 minutes)

### Narrative

In this activity, students apply previous reasoning about the size of fractions and their knowledge about fractions that are equivalent to $$\frac{1}{2}$$ to classify and compare fractions. Along the way, students have opportunities to make new observations about the structure of fractions that are less than $$\frac{1}{2}$$, greater than $$\frac{1}{2}$$ but less than 1, and greater than 1 (MP7).

The activity calls for the use of colors as a way to code fractions in different groups. If colored pencils are not available, students can code the fractions by putting circles, triangles, and squares around the fractions. In either case, a key or legend should be created.

MLR8 Discussion Supports. Encourage students to begin partner discussions by reading their written responses aloud. If time allows, invite students to revise or add to their responses based on the conversation that follows.

### Required Materials

Materials to Gather

### Required Preparation

• Each group of 2 needs 3 colored pencils (3 different colors).

### Launch

• Groups of 2
• Give each group 3 colored pencils.

### Activity

• “Tómense unos minutos en silencio para responder las primeras 4 preguntas. Después, discutan sus respuestas con su pareja” // “Take a few quiet minutes to answer the first 4 questions. Afterward, discuss your responses with your partner.”
• “Van a codificar las fracciones con colores o figuras” // “You will need to code the fractions by color or by shape.”
• 7–8 minutes: individual work time
• 5 minutes: partner discussion
• Pause for a whole-class discussion before proceeding to the last question.
• Invite students to share how they knew if a fraction is less than $$\frac{1}{2}$$, or if it is greater than $$\frac{1}{2}$$ but less than 1. Record their responses.
• “¿Cómo describirían el último grupo de fracciones que no quedaron dentro de los primeros dos grupos?” // “How did you describe the last group of fractions that don’t fall into the first two groups?” (fractions greater than 1)
• “Ahora comparen algunas fracciones en el último problema” // “Now compare some fractions in the last problem.”
• 5 minutes: individual work time

### Student Facing

Esta es la misma tabla que viste antes.
A B C D E
1 $$\frac{2}{3}$$ $$\frac{2}{5}$$ $$\frac{2}{10}$$ $$\frac{2}{12}$$ $$\frac{2}{100}$$
2 $$\frac{4}{3}$$ $$\frac{4}{5}$$ $$\frac{4}{10}$$ $$\frac{4}{12}$$ $$\frac{4}{100}$$
3 $$\frac{7}{3}$$ $$\frac{7}{5}$$ $$\frac{7}{10}$$ $$\frac{7}{12}$$ $$\frac{7}{100}$$
4 $$\frac{11}{3}$$ $$\frac{11}{5}$$ $$\frac{11}{10}$$ $$\frac{11}{12}$$ $$\frac{11}{100}$$
5 $$\frac{26}{3}$$ $$\frac{26}{5}$$ $$\frac{26}{10}$$ $$\frac{26}{12}$$ $$\frac{26}{100}$$
1. ¿Cuáles fracciones son menores que $$\frac{1}{2}$$? Marca cada una de ellas con un círculo. Después, completa esta oración:

Yo sé que una fracción es menor que $$\frac{1}{2}$$ si . . .

2. ¿Cuáles son mayores que $$\frac{1}{2}$$ pero menores que 1? Marca cada una de ellas con un color diferente (o dibuja un triángulo alrededor de cada una). Después, completa esta oración:

Yo sé que una fracción es mayor que $$\frac{1}{2}$$ pero menor que 1 si . . .

3. Marca las fracciones que no has marcado con un tercer color (o dibuja un cuadrado alrededor de cada una). ¿Cómo describirías el tamaño de estas fracciones?
4. Agrega una leyenda al lado de la tabla que muestre lo que representa cada color (o cada figura).
5. Estas son algunas parejas de fracciones de la tabla. En cada pareja, ¿cuál fracción es mayor?

1. $$\frac{2}{5}$$$$\frac{7}{10}$$
2. $$\frac{4}{10}$$$$\frac{7}{12}$$
3. $$\frac{11}{100}$$$$\frac{4}{3}$$
4. $$\frac{26}{10}$$$$\frac{11}{12}$$

### Activity Synthesis

• See lesson synthesis.

## Lesson Synthesis

### Lesson Synthesis

Invite students to share their strategies for comparing fractions in the last question of the last activity.

“¿Cómo compararon fracciones en las que ni el numerador ni el denominador eran iguales?” // “How did you compare fractions in which neither the numerator nor the denominator are the same?” (Sample response: We compared them to $$\frac{1}{2}$$ or 1.)

“¿Cómo les ayudó el código de colores (o la comparación con $$\frac{1}{2}$$ o 1)?” // “How did the color coding (or comparison to $$\frac{1}{2}$$ or 1) help?” (Sample responses:

• Knowing whether a fraction is more or less than 1, or more or less than $$\frac{1}{2}$$, can help us tell which one is greater.
• All the fractions circled in yellow [less than $$\frac{1}{2}$$] are less than all the numbers in green [greater than $$\frac{1}{2}$$ but less than 1]. All fractions in green are less than all fractions in purple [greater than 1].)