The purpose of this Warm-up is to elicit the idea that discrete diagrams can be inefficient for representing greater numbers, which will be useful when students interpret and use more abstract tape diagrams later in the lesson. While students may notice and wonder many things about the diagram, ideas and questions for how the student could better represent the comparison are the important discussion points.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
What do you notice? What do you wonder?
photograph of student work. Noah's 9 pages. connecting cube tower, 9. Clare's 8 times as many pages. connecting cubes tower, 9, repeated 5 times. connecting cube towers, 5. repeated 3 times. run off page. crossed out. Text at the bottom, quote not finished, sad face drawn.
Student Response
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Advancing Student Thinking
Activity Synthesis
“Does this diagram show that Clare read 8 times as many pages as Noah?”
“Why do you think the student who drew this diagram scribbled parts out?” (Maybe they ran out of space. There wasn’t enough room to draw all the pages the same size and keep them together in groups.)
“What might be challenging about drawing each page when there are a lot of objects?” (It takes a lot of time and space. You might lose count.)
“What other ways could you make a diagram to show greater amounts?” (Use numbers instead of drawing each part.)
“Today we are going to look at diagrams that show comparisons with greater numbers, and think about when we might use them to represent and solve our own problems.”
Activity 1
Standards Alignment
Building On
Addressing
4.OA.A.1
Interpret a multiplication equation as a comparison, e.g., interpret as a statement that 35 is 5 times as many as 7 and 7 times as many as 5. Represent verbal statements of multiplicative comparisons as multiplication equations.
The purpose of this activity is for students to interpret and solve multiplicative comparison problems. Students interpret tape diagrams that label each box with a value, which is different from the discrete diagrams from previous lessons. They also write equations to represent the situations and explain how the equations connect to the tape diagrams (MP2). The problems in this activity have unknown lesser quantities, greater quantities, or multipliers. Questions are provided to support students in representing the unknown in tape diagrams and in identifying the unknown in given situations.
Action and Expression: Develop Expression and Communication. Provide alternative options for expression. Encourage students to examine each diagram first and write down or talk about what they know with a partner before answering each set of questions. Supports accessibility for: Visual-Spatial Processing, Language
Launch
Groups of 2
Display and read the first problem.
30 seconds: quiet think time
1 minute: partner discussion
“Is 15 pages too high or too low of an estimate for Andre?” (Too low, because the diagram shows he should have read more than Mai.)
“If Andre read 9 times as many pages as Mai, what number should replace the question mark in the diagram? Why?” (135, because the 9 rectangles represent 9 times as many as 15. There should be 9 fifteens.)
30 seconds: quiet think time
1 minute: partner discussion
Activity
3 minutes: independent work time
8 minutes: partner work time
Monitor for students who:
Explain the connection between their equations and the diagram.
Show understanding that each rectangle represents the same amount.
Mai and Andre compare the numbers of pages they read on the first day of the reading competition.
diagram. two rectangles. bottom rectangle, Andre's pages. partitioned into 9 equal parts, total length question mark. Top rectangle, Mai's pages. Same size as one of 9 parts of bottom rectangle, labeled 15.
What would be a good estimate for the number of pages Andre read?
The diagram shows the pages Lin and Kiran each read on 1 day of the reading competition.
diagram. two rectangles. bottom rectangle, Kiran's pages. partitioned into 6 equal parts each labeled 9, total length question mark. Top rectangle, Lin's pages. Same size as one of 6 parts of bottom rectangle, labeled 9.
Complete the statement and explain how you know.
Kiran read _____ times as many pages as Lin.
Write a multiplication equation that compares the pages read by Lin and by Kiran.
How many total pages did Kiran read?
Jada read some pages. Han read 60 pages altogether.
diagram. two rectangles. bottom rectangle, Han's pages. partitioned into 3 equal parts each labeled question mark, total length 60. Top rectangle, Jada's pages. Same size as one of the 3 parts of bottom rectangle, labeled question mark.
How many times as many pages as Jada did Han read? Explain how you know.
Write a multiplication equation to compare the pages Han read with the number of pages Jada read. Use a symbol to represent the unknown.
How many pages did Jada read? Explain how you know.
Elena reads 72 pages. Clare reads 9 pages.
diagram. two rectangles. bottom rectangle, Elena's pages. partitioned into 2 parts. One part labeled 9. Other part unknown. total length, 42. Top rectangle, Clare's pages, same length as left part of bottom rectangle, also labeled 9.
How is this diagram different from the earlier diagrams?
Write a multiplication equation to compare the pages read by Elena and by Clare. Use a symbol to represent the unknown.
How many times the number of pages as Clare does Elena read?
Student Response
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Advancing Student Thinking
If students write equations without unknowns, consider asking:
“What information do you know from looking at the diagram? What information is unknown?
"What equation could you write to represent this situation? Use a symbol to represent the unknown value.”
Activity Synthesis
Select 2–3 students to share their responses and their reasoning.
“How do the diagrams help us figure out what we know about the situation and what we need to find out?” (Each diagram shows two quantities being compared, and the ‘times as many’ amount that compares them. The quantity that is missing is the part we need to find out.)
“How do the diagrams show ‘times as many’?” (‘Times as many’ is represented by the number of times each rectangle in the diagram is repeated.)
Display:
“How does this equation help us find the number of pages Jada read?” (We know that Han read 60 pages, which is 3 times as many as Jada, because the diagram shows 3 equal-size rectangles for Han and one rectangle for Jada. We just need to know the amount that each rectangle represents, which will be the amount of pages that Jada read.)
Activity 2
Standards Alignment
Building On
Addressing
4.OA.A.2
Multiply or divide to solve word problems involving multiplicative comparison, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem, distinguishing multiplicative comparison from additive comparison.See Glossary, Table 2.
The purpose of this activity is for students to represent multiplicative comparison situations and solve for an unknown factor or unknown product.
In the Activity Synthesis, students make connections between the description, their diagram, and multiplication equations that represent the situation (MP2).
MLR8 Discussion Supports. Synthesis: At the appropriate time, give students 2–3 minutes to make sure everyone in their group can explain “strategy,” “equation,” and “diagram.” Invite groups to rehearse what they will say when they share with the whole class. Advances: Speaking, Conversing, Representing
Launch
Groups of 2
Read directions for the activity aloud.
“What will we do with each problem in this task?” (Write an equation, with the unknown represented by a symbol, draw a diagram to show comparison, and answer the question.)
Activity
4 minutes: independent work time
2 minutes: partner discussion about the first problem
“Share with your partner how you represented the unknown value in your diagram and in your equation.”
“Work with your partner on the rest of the problems.”
8 minutes: partner work time
Monitor for students who:
Draw and label each comparison.
Identify and represent the unknown in their equation and in their diagram.
Use “times as many” language to describe each comparison.
If students finish early, they can create their own situation and question, and then trade with their partner. The partner will write the equation, draw a diagram, and answer the question.
For each situation:
Write an equation to represent the situation. Use a symbol to represent the unknown.
Draw a diagram to show the comparison.
Answer the question about the situation.
Lin read 7 books. Diego read 8 times as many books as Lin.
Equation:
Diagram:
How many books did Diego read?
Tyler has some books. Clare has 72 books, which is 12 times as many books as Tyler.
Equation:
Diagram:
How many books does Tyler have?
Noah read 13 books. Elena read 130 books.
Equation:
Diagram:
Complete the statement:
_______________ read _____ times as many books as _______________.
Student Response
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Advancing Student Thinking
Activity Synthesis
“What information did you use in each situation to know how to draw each diagram?”
The number of repeating rectangles in the greater quantity represents “times as many.”
The row with one rectangle is the amount being multiplied.
The row with multiple rectangles represents the greater quantity in the comparison.
“How is the last problem different from the first two?” (The unknown value is how many “times as many.”)
Lesson Synthesis
“Today we used diagrams to compare two large quantities.”
Display some diagrams students created to represent
“What do you notice about the different diagrams we used to represent this equation?” (6 sets of 12 or 12 sections, with 6 in each)
“Why might we represent the diagram with a number, instead of drawing out all the parts?” (Drawing all the amounts would take a while and may result in a counting mistake or take up too much space.)
“Diagrams that use numbers to show the quantities are a helpful tool for showing ‘_____ times as many’ situations because they can represent any amount.”
Standards Alignment
Building On
Addressing
4.OA.A.2
Multiply or divide to solve word problems involving multiplicative comparison, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem, distinguishing multiplicative comparison from additive comparison.See Glossary, Table 2.
Multiply or divide to solve word problems involving multiplicative comparison, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem, distinguishing multiplicative comparison from additive comparison.See Glossary, Table 2.