The purpose of this Estimation Exploration is for students to estimate the area of a shaded region. In a previous Estimation Exploration, students looked at a shaded region where the length was represented by a unit fraction and the width could be estimated with a unit fraction. In the diagram, the length is a unit fraction. The width can not be a unit fraction since it is greater than . This prepares students for the work of this lesson which is to consider products of a unit fraction and a non-unit fraction.
Launch
Groups of 2
Display the image.
“¿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 Task Statement
¿Cuál es el área de la región coloreada?
Escribe una estimación que sea:
muy baja
razonable
muy alta
Student Response
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Advancing Student Thinking
Activity Synthesis
“¿El área de la región coloreada es más o menos que de unidad cuadrada? ¿Cómo lo saben?” // “Is the area of the shaded region more or less than square unit? How do you know?” (It’s more because of is , and more than that is shaded.)
Activity 1
15 mins
Escribamos ecuaciones
Standards Alignment
Building On
Addressing
5.NF.B.4.b
Find the area of a rectangle with fractional side lengths by tiling it with unit squares of the appropriate unit fraction side lengths, and show that the area is the same as would be found by multiplying the side lengths. Multiply fractional side lengths to find areas of rectangles, and represent fraction products as rectangular areas.
The purpose of this activity is for students to write expressions for and find the area of shaded regions whose side lengths are a unit fraction and a non-unit fraction. Students look at a series of diagrams with an increasingly large shaded region so they can look for and make use of structure (MP7).
It is important to relate the work here to what students have already learned about the product of a unit fraction and a unit fraction. This is the goal of the Activity Synthesis. For example, students have seen that . Since is six s, the product will be six s or .
MLR8 Discussion Supports. Prior to solving the problems, invite students to make sense of the situations and take turns sharing their understanding with their partner. Listen for and clarify any questions about the context. Advances: Listening, Conversing
Launch
Groups of 2
Display Diagram A from the student book.
“¿Cuál es una expresión de multiplicación que representa la región coloreada?” // “What is a multiplication expression that represents the shaded region?”(, )
“¿De qué manera el diagrama representa su expresión?” // “How does the diagram represent your expression?”(There is of the first row shaded and that row is of the square. There are 2 shaded pieces and each is of the whole square.)
Activity Synthesis
Ask previously selected students to share the patterns they noticed in the table.
Display the expression from the last problem: .
“¿De qué manera el diagrama muestra ?” // “How does the diagram show ?” (The first row of pieces in a square is of the square.)
“¿De qué manera el diagrama muestra ?” // “How does the diagram show ?” (There are 6 pieces shaded and each one is of the row.)
“¿De qué manera el diagrama muestra ?” // “How does the diagram show ?” (There is of a row shaded and that row is of a square unit.)
Activity 2
20 mins
Estimemos con expresiones
Standards Alignment
Building On
Addressing
5.NF.B.4.b
Find the area of a rectangle with fractional side lengths by tiling it with unit squares of the appropriate unit fraction side lengths, and show that the area is the same as would be found by multiplying the side lengths. Multiply fractional side lengths to find areas of rectangles, and represent fraction products as rectangular areas.
The purpose of this activity is for students to write multiplication expressions to estimate the area of a shaded region. This builds on the Warm-up and the Activity Launches by asking students to write an expression for the shaded region in the image they considered in the Warm-up.
This work in this activity combines the skill of estimation with an understanding that the area of a rectangle relates to its length and width. So far, students have only calculated these areas as products of fractions when at least one side length is a unit fraction. Students may write products of two non-unit fractions. While they have not yet learned how to calculate these products and relate them to areas, these answers are valid when the estimates are reasonable and students will learn in the next lesson how to find the value of these expressions.
Action and Expression: Internalize Executive Functions. Synthesis: Invite students to plan a strategy, including the tools they will use, for estimating the area of the shaded rectangle. If time allows, invite students to share their plan with a partner before they begin. Supports accessibility for: Conceptual Processing, Language
Launch
Groups of 2
Display the image from the Warm-up: “¿Cuál expresión de multiplicación podría representar el área de la región coloreada?” // “What multiplication expression might represent the area of the shaded region?” (