This Warm-up prompts students to carefully analyze and compare different diagrams that represent products of fractions. In making comparisons, students have a reason to use language precisely (MP6). The Warm-up also enables the teacher to listen to students as they share their interpretations of the various representations of fraction multiplication, and use their developing vocabulary to describe the characteristics of fractional products.
Launch
Groups of 2
Display the image.
“Pick 3 that go together. Be ready to share why they go together.”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
2–3 minutes: partner discussion
Share and record responses.
Student Task Statement
Which 3 go together?
A
B
C
D
Student Response
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Advancing Student Thinking
Activity Synthesis
“How does Diagram A represent the expression ?” (There is a half shaded and then a third of the half is shaded darker.)
Activity 1
20 mins
Interpret Diagrams
Standards Alignment
Building On
Addressing
5.NF.B.4.a
Interpret the product as parts of a partition of into equal parts; equivalently, as the result of a sequence of operations . For example, use a visual fraction model to show , and create a story context for this equation. Do the same with . (In general, .)
The purpose of this activity is for students to draw two diagrams that represent a unit fraction of a unit fraction. Students work with the same unit fractions in both diagrams. The directions were intentionally written to encourage students to partition a unit square in different ways. Students initially partition the square into thirds in the first problem and into fourths in the second problem. Students may complete the diagrams in a way that makes sense to them. During the Activity Synthesis, students will connect both of the diagrams to the expressions and .
Launch
Groups of 2
Activity
2 minutes: Independent work time
10 minutes: partner work time
Monitor for students who:
Draw diagrams like those in the student responses.
Recognize that both diagrams have the same amount shaded.
Explain the different ways they partitioned each diagram.
Student Task Statement
Show of the square.
Shade of of the square.
How much of the whole square is shaded?
Show of the square.
Shade of of the square.
How much of the whole square is shaded?
How are the diagrams alike? How are they different?
Activity Synthesis
Ask previously selected students to share their responses in the order given.
“How are the diagrams the same?” (They both have and in them. They both have of the whole square shaded.)
“How are the diagrams different?” (In one diagram, I started by showing of the square and then shaded in of . In the other diagram, I started by showing of the square and then shaded in of .)
Display:, ,
“How do the diagrams represent these expressions?”
Adapt diagrams as needed in order to show all three expressions.
“How do we know that both squares have the same amount shaded?” (They both have shaded.)
Activity 2
15 mins
Write an Expression
Standards Alignment
Building On
Addressing
5.NF.B.4.a
Interpret the product as parts of a partition of into equal parts; equivalently, as the result of a sequence of operations . For example, use a visual fraction model to show , and create a story context for this equation. Do the same with . (In general, .)
The purpose of this activity is for students to deepen their understanding of the relationship between diagrams and multiplication expressions. The expressions are products of unit fractions. Students start with a diagram and first explain how an expression represents the diagram. Then they write their own expression representing a different diagram (MP7).
This activity uses MLR2 Collect and Display. Advances: Reading, Writing.
Representation: Internalize Comprehension. Synthesis: Invite students to identify which details were most important to represent the shaded piece with a multiplication expression. Display the sentence frame: “The next time I write a multiplication expression to represent the shaded part of a square, I will look for . . . .” Supports accessibility for: Conceptual Processing, Memory
Launch
Groups of 2
Activity
2 minutes: independent work time
5–7 minutes: partner work time
MLR2 Collect and Display
Circulate to listen for and collect the language students use to describe where they see how Priya’s diagram represents the expressions. Listen for: columns, rows, fifths, halves, tenths, number of pieces, size of the piece. Record students’ words and phrases on a visual display and update it throughout the lesson.
Student Task Statement
Priya shaded part of a square.
How does the expression represent the area of the shaded part? Explain or show your reasoning.
How does the expression represent the area of the shaded part? Explain or show your reasoning.
Write a multiplication expression to represent the area of the shaded piece. Explain or show your reasoning.
How much of the whole square is shaded?
Activity Synthesis
“Are there any other words or phrases that are important to include on our display?”
Ask students to clarify the meaning of a word or phrase.
As students share responses, update the display, by adding (or replacing) language, diagrams, or annotations.
Remind students to borrow language from the display as needed.
Display Priya’s diagram and these expressions:
“How does Priya’s diagram show each expression?” (The rows show halves and of one of the rows is shaded. The columns show fifths and of one of the columns is shaded.)
Display the second diagram in the activity.
“How does the shaded piece in the diagram represent ?” (The square is divided into three columns and each of those columns is divided into 5 rows. The shaded part is of one of the columns.)
“How does the shaded piece represent ?” (The square is divided into 5 rows and each row is divided into 3 columns. The shaded piece is of one of the rows.)
“How much of the whole rectangle is shaded?” ()
Lesson Synthesis
“Today we wrote multiplication expressions to represent shaded rectangles. We also wrote fractions to represent the size of the shaded piece.”
Display the second image from the second activity.
Display the equations and .
“How do you know these equations are true?” (We can see that the shaded part of the diagram is both of the whole and of the whole. We can also see because the whole square is divided into 15 equal pieces and one of the equal pieces is shaded.)
“In this lesson we saw that ...”
Display:
“This is always true. We can multiply fractions in any order and get the same result.”
Have feedback on the curriculum?
Help us improve by sharing suggestions or reporting issues.
Interpret the product as parts of a partition of into equal parts; equivalently, as the result of a sequence of operations . For example, use a visual fraction model to show , and create a story context for this equation. Do the same with . (In general, .)