This Number Talk encourages students to rely on their knowledge of multiplication, place value, and properties of operations to mentally solve division problems. The reasoning elicited here helps to develop students' fluency with multiplication and division within 100.
To find the quotients of greater numbers, students need to look for and make use of structure in quotients that have less value or are more familiar, or rely on the relationship between multiplication and division (MP7).
Launch
Display one expression.
“Hagan una señal cuando tengan una respuesta y puedan explicar cómo la obtuvieron” // “Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Activity
Record answers and strategies.
Keep expressions and work displayed.
Repeat with each expression.
Encuentra mentalmente el valor de cada expresión.
Student Response
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Advancing Student Thinking
Activity Synthesis
“¿Cómo les ayudaron las primeras expresiones a encontrar los valores de las últimas expresiones?” // “How did the earlier expressions help you find the values of the later expressions?”
Consider asking:
“¿Alguien usó la misma estrategia, pero la explicaría de otra forma?” // “Did anyone have the same strategy but would explain it differently?”
“¿Alguien pensó en el problema de otra forma?” // “Did anyone approach the problem in a different way?”
Activity 1
Standards Alignment
Building On
Addressing
3.NF.A.3.c
Express whole numbers as fractions, and recognize fractions that are equivalent to whole numbers. Examples: Express in the form ; recognize that ; locate and at the same point of a number line diagram.
The purpose of this activity is for students to place fractions greater than 1 on the number line, and to notice how fractions can be written as whole numbers. For example, students will see that for halves, every second half is located at a whole number because it takes two halves to make a whole.
Students work in groups. Each member will be assigned a different set of fractions to put on their number line so that the group can look for patterns across halves, thirds, and fourths. Through repeated reasoning, students may notice two types of regularity (MP8):
It takes 2 halves, 3 thirds, or 4 fourths to make a whole.
Whole numbers appear regularly (every 2 halves, every 3 thirds).
Launch
Groups of 3
Assign one set of fractions to each student in the group.
Activity
“Tómense unos minutos para ubicar y marcar en la recta numérica las fracciones que les asignaron” // “Take a few minutes to locate and label your assigned fractions on the number line.”
2–3 minutes: independent work time
“Compartan con su grupo su estrategia para ubicar las fracciones, y entre todos busquen patrones en los números” // “Share your strategy for locating the fractions with your group, and look for patterns in the numbers together.”
4–6 minutes: small-group discussion
Monitor for students who:
Notice that every 2 halves, 3 thirds, and 4 fourths ends up at a whole number.
Notice that the numerator is a multiple of the denominator.
Ubica y marca en la recta numérica las fracciones que te asignaron. Prepárate para explicar tu razonamiento.
Hagan una lista de todas las fracciones que estaban ubicadas en un número entero. Incluyan las de las 3 rectas numéricas del grupo.
¿Qué patrones ves en todas las 3 rectas numéricas que marcaron?
Student Response
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Advancing Student Thinking
Activity Synthesis
Display 3 blank number lines from 0 to 5 to label as students share.
Select previously identified students to share the patterns they noticed in the fractions that share the same locations as the whole numbers.
Label the number line as students share, with the whole numbers written as , , , and so on, to highlight the idea that the number of equal parts (2, 3, or 4) in the fractions affects the number of parts needed to end up at a whole number.
“¿Por qué puede tener sentido que las fracciones muestren esos patrones?” // “Why might it make sense that the fractions show those patterns?” (It takes 2 halves, 3 thirds, or 4 fourths to make a whole. There are 2 halves in 1, so there are or 4 halves in 2, or 6 halves in 3, and so on.)
Activity 2
Standards Alignment
Building On
Addressing
3.NF.A.2
Understand a fraction as a number on the number line; represent fractions on a number line diagram.
The purpose of this activity is for students to use the location of a unit fraction to locate 1 and 2 on a number line. It is likely that students will reason about repeating the size of the unit fraction to locate 1. They may continue to count unit-fraction-size parts to locate 2, or use the location of 1.
MLR1 Stronger and Clearer Each Time. Synthesis: Before the whole-class discussion, give students time to meet with 2 or 3 partners to share and get feedback on their response to “¿Cómo ubicaron 1 cuando les daban la ubicación de una fracción unitaria?” // “How did you locate 1 when given the location of a unit fraction?” Invite listeners to ask questions, to press for details, and to suggest mathematical language. Give students 2–3 minutes to revise their written explanation or representation, based on the feedback they receive. Advances: Writing, Representing, Speaking, Listening
Representation: Internalize Comprehension. Synthesis: Invite students to identify which details were needed or most useful to solve the problem. Display the sentence frame: “La próxima vez que ubique el 1 en una recta numérica, buscaré / prestaré atención a . . . .” // “The next time I locate 1 on a number line, I will look for/pay attention to . . . ” Supports accessibility for: Conceptual Processing
Launch
Groups of 2
Display the number line with marked.
“¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?” (Students may notice: The number line only has 0 on one end and no whole number on the other end. One-half is labeled. Students may wonder: Is the number line partitioned into halves? Where is 1? What other numbers are on the number line? Why is nothing marked after ?)
1 minute: quiet think time
“Discutan con su pareja lo que pensaron” // “Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Activity
“Tómense unos minutos para ubicar el 1 en estas rectas numéricas” // “Take a few minutes to locate 1 on these number lines.”
3–5 minutes: independent work time
“Compartan sus estrategias con su pareja y hablen sobre cómo pueden ubicar el 2 en estas rectas numéricas” // “Share your strategies with your partner and talk about how you might locate 2 on these number lines.”
3–5 minutes: partner work time
Monitor for students who:
Iterate the size of the unit fraction, using tick marks.
Make unit-fraction-size jumps to count up to 1.
Realize there will be 4 one-fourths in 1, for example, and place the 1 before placing and .
Activity Synthesis
Invite students to share a variety of strategies or representations of the number line for locating 1 when given the location of a unit fraction.
Consider asking:
“¿Alguien lo pensó de una forma parecida?” // “Did anyone think about it in a similar way?”
“¿Alguien quiere agregar algo al razonamiento de ____?” // “Does anyone want to add on to ____ 's reasoning?”
“¿Qué observaron acerca de cómo ubicaron el 1 las distintas personas?” // “What did you notice about how different people located 1?” (They marked off the lengths of the unit fraction until reaching 1 whole. They used a multiple of a unit fraction and marked off that length as many times as needed to get 1 whole.)
“¿Qué estrategias usaron para ubicar el 2 después haber ubicado el 1?” // “What strategies did you have for locating 2 once you had located 1?”
Lesson Synthesis
“Hoy vimos que algunas fracciones se ubicaban en los mismos puntos que los números enteros. ¿Cuáles son algunos ejemplos de esto? // “Today we saw that some fractions were located at the same points as whole numbers. What were some examples of this?” (, , )
“¿Cómo podemos explicar que haya fracciones y números enteros en la misma ubicación en la recta numérica?” // “How could we explain that fractions and whole numbers were in the same locations on the number line?” (Every 2 halves (or 3 thirds or 4 fourths) is a whole number, so if I go 2 halves, I am at 1. If I moved another 2 halves (or 3 thirds or 4 fourths), I would be at , which is at the next whole number, 2.)
Standards Alignment
Building On
Addressing
3.OA.C.7
Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that , one knows ) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
Ubica y marca el 1 en cada recta numérica. Prepárate para explicar tu razonamiento.
¿Cómo puedes ubicar el 2 en las rectas numéricas del problema anterior?
Student Response
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Advancing Student Thinking
If students don’t locate 1, consider asking:
“Dime qué has intentado hacer para ubicar el 1” // “Tell me how you’ve tried to locate 1.”
“¿Cuántos medios (tercios, cuartos u octavos) hay en 1? ¿Cómo podemos usar eso para ubicar el 1?” // “How many halves (or thirds, fourths, or eighths) are in 1? How could we use that to locate 1?”