This Number Talk encourages students to look for structure in multiplication expressions and to rely on properties of operations to mentally solve problems. Reasoning about products of whole numbers helps to develop students’ fluency.
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.
Student Task Statement
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 el valor de la última expresión?” // “How did the earlier expressions help you find the value of the last expression?”
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
20 mins
Mostremos la equivalencia
Standards Alignment
Building On
Addressing
3.NF.A.3.a
Understand two fractions as equivalent (equal) if they are the same size, or the same point on a number line.
The purpose of this activity is for students to use diagrams to reason about equivalence and to reinforce their awareness of the relationship between fractions that are equivalent.
Students show that a shaded diagram can represent two fractions, such as and , by further partitioning given parts or by composing larger parts from the given parts. Unlike with the fraction strips, where different fractional parts are shown in rows and students could point out where and how they see equivalence, here students need to make additional marks or annotations to show equivalence.
In upcoming lessons, students will extend similar strategies to reason about equivalence on a number line—by partitioning the given intervals on a number line into smaller intervals or by composing larger intervals from the given intervals.
In the first problem, students construct a viable argument in order to convince Tyler that of the rectangle is shaded (MP3).
Action and Expression: Develop Expression and Communication. Synthesis: Identify connections between strategies that result in the same outcomes but use different approaches. Supports accessibility for: Memory, Visual-Spatial Processing
Launch
Groups of 2
Activity
“Trabajen con su compañero en el primer problema. Discutan si están de acuerdo o no con Jada y muestren su razonamiento” // “Work with your partner on the first problem. Discuss whether you agree with Jada and show your reasoning.”
3–4 minutes: partner work time
Pause for a brief discussion. Invite students to share their responses and their reasoning.
“Ahora trabajen individualmente en el resto de la actividad” // “Now, work independently on the rest of the activity.”
5 minutes: independent work time
Monitor for the different strategies students use to show equivalence, such as:
Drawing circles or brackets to show composing larger parts from the given parts.
Drawing lines to show new partitions.
Labeling parts of the fractions with two names.
Drawing a new diagram with different partitions but the same shaded amount.
Identify students, who use different strategies, to share during the Activity Synthesis.
Student Task Statement
El diagrama representa 1.
¿Qué fracción representa la parte sombreada del diagrama?
Jada dice que representa . Tyler no está seguro.
¿Estás de acuerdo con Jada? Si es así, explica o muestra cómo convencerías a Tyler de que Jada tiene razón. Si no, explica o muestra tu razonamiento.
Cada diagrama representa 1.
Muestra que la parte sombreada de este diagrama representa tanto como .
Muestra que la parte sombreada de este diagrama representa tanto como .
Muestra que la parte sombreada de este diagrama representa tanto como .
Activity Synthesis
Select previously identified students to share their responses and their reasoning. Display their work for all to see.
As students explain, describe the strategies they use to show equivalence. Ask if others in the class showed equivalence the same way.
Activity 2
15 mins
Más de un nombre
Standards Alignment
Building On
Addressing
3.NF.A.3.a
Understand two fractions as equivalent (equal) if they are the same size, or the same point on a number line.
The purpose of this activity is for students to generate equivalent fractions, including for fractions greater than 1, given partially shaded diagrams. Students may use strategies from an earlier activity—partitioning a diagram into smaller equal parts, or making larger equal parts out of existing parts—or patterns they observed in the numerators and the denominators of equivalent fractions (MP7).
MLR8 Discussion Supports. Students should take turns naming the equivalent fractions they described and explaining their reasoning to their partner. Display the following sentence frame for all to see: “Observé _____, entonces pensé . . .” // “I noticed _____ , so I thought . . . .” Encourage students to challenge each other when they disagree. Advances: Speaking, Representing
Launch
Groups of 2
Display or draw a diagram with 2 fourths shaded:
“Observen que hay un 1 debajo del diagrama. Esta es otra forma de mostrar qué parte del diagrama representa 1” // “Notice there's a 1 below the diagram. This is another way to show which part of the diagram represents 1.”
“¿Qué fracciones pueden estar representadas por las partes sombreadas del diagrama?” // “What fractions can the shaded parts of the diagram represent?” ()
Activity
“Ahora escriban dos fracciones que puedan representar las partes sombreadas de cada diagrama” // “Now write two fractions that can represent the shaded parts of each diagram.”
3–5 minutes: independent work time
“Discutan con su compañero cómo llamaron a las fracciones equivalentes. Asegúrense de compartir cómo razonaron en cada caso” // “Discuss with your partner the equivalent fractions you named. Be sure to share your reasoning for each fraction.”
2–3 minutes: partner discussion
Monitor for students who make statements such as:
The first diagram is because 4 of the 6 equal parts are shaded. It's also because every 2 sixths is 1 third, and 2 of the 3 thirds are shaded.
The second diagram is because 2 of the 8 equal parts are shaded. It's also because every 2 eighths is 1 fourth, and 1 of the 4 fourths is shaded.
Student Task Statement
Cada diagrama representa 1. Escribe dos fracciones que representen la parte sombreada de cada diagrama.
Este es otro diagrama.
¿Qué fracción está representada por la parte sombreada del diagrama?
Escribe otra fracción que esté representada por esta parte.
Student Response
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Advancing Student Thinking
If students name a fraction based only on the given partitions, consider asking:
“Cuéntame cómo llamaste a la fracción” // “Tell me how you named the fraction.”
“¿Cómo puedes usar el diagrama para encontrar una fracción equivalente?” // “How could you use the diagram to find an equivalent fraction?”
Activity Synthesis
Select students to share their strategies for writing equivalent fractions for each diagram. Display the diagrams they marked or annotated.
“¿En qué se diferenciaba el último diagrama de los tres primeros?” // “In what ways was the last diagram different from the first three?” (It shows 2 wholes. The shaded parts were greater than 1.)
“¿Su estrategia para encontrar fracciones equivalentes en este diagrama fue diferente a la que usaron en los tres primeros? ¿Por qué sí o por qué no?” // “Was your strategy for finding equivalent fractions for this diagram different from the first three? Why or why not?” (No, it still involved making smaller equal parts. Yes, I partitioned the first 1 whole and the second 1 whole separately.)
If no students mention for the last diagram, ask, “¿Pueden mencionar una fracción distinta a y ?” // “Can you name an equivalent fraction other than and ?”
Lesson Synthesis
“Hoy vimos que las partes sombreadas de un diagrama pueden ser representadas por varias fracciones equivalentes” // “Today we saw that the shaded parts of a diagram can be represented by multiple equivalent fractions.”
Display a diagram of labeled fraction strips from an earlier activity, and a couple of shaded diagrams that show equivalent fractions from this activity.
“¿Cómo usamos las tiras de fracciones como ayuda para ver fracciones equivalentes y darles un nombre?” // “How did we use the fraction strips to help us see and name equivalent fractions?” (We could see if some number of parts in one row is the same size as the parts in another row. The labels on the strips help us name the fractions that are equivalent.)
“¿Cómo nos ayudaron los diagramas sombreados de esta actividad a ver fracciones equivalentes y darles un nombre?” // “How did the shaded diagrams in this activity help us see and name equivalent fractions?” (We could either partition the diagram into smaller equal parts, or put the parts together to make larger equal parts.)
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Apply properties of operations as strategies to multiply and divide.Students need not use formal terms for these properties.Examples: If is known, then is also known. (Commutative property of multiplication.) can be found by , then , or by , then . (Associative property of multiplication.) Knowing that and , one can find as . (Distributive property.)
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.