options: Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.

Number Systems and Quantity: students learn to understand the complex number system and reason quantitatively.

Measurement & Data: students learn to work with data and measure attributes such as time, money, length, area, and volume. They may learn to compare measurements to operations and convert between different units of measure.

Operations & Algebra: students learn to solve problems using algebraic thinking and operations such as addition, subtraction, multiplication, and division. They may learn to identify and explain arithmetic patterns, evaluate or manipulate numerical expressions, and reason with equations and inequalities.

Ratios & Proportional Relationships: students learn to recognize, describe, represent, and reason with ratios, rates, proportional relationships, and percent.

Modeling: students learn to choose and use appropriate mathematics and statistics to analyze real-world empirical situations, improve decisions, and report on their conclusions and the reasoning behind them.

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.

Statistics & Probability: students learn to analyze and produce data distributions, and build understanding of univariate and bivariate data. They learn to interpret data, make statistical inferences, justify conclusions, understand rules of probability, and use probability to make decisions.

Counting & Cardinality: students learn to know number names and the count sequence, count to tell the number of objects, and compare numbers.

Geometry: students learn to classify geometric figures by their properties, and understand and compare the relationships between them. Students develop and use formulas to compute lengths, areas, and volumes, and they use transformations to generate new shapes and compare existing ones. Geometry can be studied with and without coordinates.

Functions: students learn to define, use, and evaluate functions to model relationships between quantities.
problem_activity: Narrative
The purpose of this activity is for students to notice structure in a series of diagrams and the expressions that represent them. They investigate how these expressions vary as the number of rows and columns in the diagram change. Students see how the diagram represents the multiplication expression and also how the diagram helps to find the value of the expression (MP7). Through repeated reasoning they also begin to see how to find the value of a product of any two unit fractions (MP8).
Launch
Groups of 2
Display the images from the task.
“What is different about these diagrams?” (The number of rows increases by 1. The blue shaded piece gets smaller.)
“What is the same?” (The size of the big square. There are always 4 columns. Only one piece is shaded.)
1 minute: quiet think time
Share and record responses.
Activity
1–2 minutes: independent work time to complete the first problem
1–2 minutes: partner discussion
“Now, complete the rest of the problems with your partner.”
5 minutes: partner work time
Monitor for students who:
choose different diagrams to represent with multiplication expressions
represent the same diagram with different multiplication expression, for example,
\(\frac{1}{2}\times\frac{1}{4}\)
and
\(\frac{1}{4}\times\frac{1}{2}\)
Student Facing
A
[IMG]
B
[IMG]
C
[IMG]
D
[IMG]
Choose one of the diagrams and write a multiplication expression to represent the shaded region. How much of the whole square is shaded? Explain or show your thinking.
If the pattern continues, draw what you think the next diagram will look like. Be prepared to explain your thinking.
[IMG]
Student Response
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Advancing Student Thinking
If students do not write correct expressions to represent the diagrams, write the correct expressions and ask, “How do the expressions represent the area of the shaded piece of the diagram?”
Activity Synthesis
Display the diagrams from the student workbook.
Select previously identified students to share.
As students explain where they see the multiplication expression in each diagram, record the expressions under the diagram for all to see.
Refer to the diagram that shows
\(\frac{1}{2}\times\frac{1}{4}\)
or
\(\frac{1}{4}\times\frac {1}{2}\)
.
Display both expressions.
“How does this diagram represent both of these expressions?” (It shows one half of one fourth shaded in and it also shows one fourth of one half shaded in.)
Represent student explanation on the diagrams.
“Why is the area of the shaded region getting smaller in each diagram?” (Because we are shading a smaller piece of
\(\frac{1}{4}\)
each time.)
Display:
\(\frac{1}{2} \times \frac{1}{4}= \frac{1}{2\times 4}=\frac{1}{8}\)
\(\frac{1}{3} \times \frac{1}{4}= \frac{1}{3\times 4}=\frac{1}{12}\)
\(\frac{1}{4} \times \frac{1}{4}= \frac{1}{4\times 4}=\frac{1}{16}\)
\(\frac{1}{5} \times \frac{1}{4}= \frac{1}{5\times 4}=\frac{1}{20}\)
“These equations represent the diagrams. What patterns do you notice?” (They all have
\(\frac {1}{4}\)
in them. The denominators in the first fractions go 2, 3, 4, 5. The denominators in the middle fractions are multiplication expressions, the denominators in the middle are all multiplied by 4, the denominator in the fraction that shows the value of the shaded piece goes up by 4 each time.)
“How do the diagrams represent
\(\frac{1}{2\times 4}\)
,
\(\frac{1}{3\times4}\)
,
\(\frac{1}{4\times4}\)
,
\(\frac{1}{5\times4}\)
?” (The numerator tells us that there is 1 piece shaded and the denominator tells us the size of the piece. The denominator also tells us the rows and columns that the whole is divided into.)


correct_option_index: 0