standard_description: Prove theorems about triangles. Theorems include: a line parallel to one side of a triangle divides the other two proportionally, and conversely; the Pythagorean Theorem proved using triangle similarity.
problem_activity: Activity
The mathematical purpose of this activity is to give students a chance to practice finding data displays that represent the distribution of the same data set and using precise vocabulary for describing the shape of the distributions while taking turns matching cards. Students trade roles explaining their thinking and listening, providing opportunities to explain their reasoning and critique the reasoning of others (MP3).
Launch
Arrange students in groups of 2. Display the images of the dot plot and histogram. Ask students what they notice and wonder.
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If it does not come up, help students notice that these two data displays show the same data in different formats. They can also be described as skewed right.
Give each group a set of cut-up cards. Explain that a match is two different displays that represent the distribution of the same set of data. Ask students to take turns: the first partner identifies a match, explains why they think it is a match, then describes the distribution while the other student listens and works to understand. Then they switch roles.
Student Facing
Take turns with your partner matching 2 different data displays that represent the distribution of the same set of data.
For each set that you find, explain to your partner how you know it’s a match.
For each set that your partner finds, listen carefully to their explanation. If you disagree, discuss your thinking and work to reach an agreement.
When finished with all ten matches, describe the shape of each distribution.
Student Response
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Anticipated Misconceptions
For students having trouble with the uniform distribution histograms, remind them that the lower bound for each interval is included and the upper bound is not. Ask them why this might change the last bar in each of these histograms. Some students may not know where to start to match data displays. You can tell them to look at the lowest and highest values as a starting point to finding similarities between two representations.
Activity Synthesis
Once all groups have completed the matching, discuss the following:
“Which matches were tricky? Explain why.” (The uniform distributions may be difficult.)
“What vocabulary was useful to describe the shape of the distribution?” (symmetric, skewed, uniform, bimodal, bell-shaped)
“Were there any matches that could be described by more than one of these vocabulary terms?” (Yes, symmetric or skewed can also be used with some of the other terms for some of the distributions.)
If necessary, ask students to revoice less formal descriptions of the shape of the distribution using formal language including:
Symmetric distribution
Skewed distribution
Uniform distribution
Bimodal distribution
Bell-shaped distribution
Speaking, Listening: MLR 7 Compare and Connect.
Ask students to prepare a visual display of their sorted cards. As students investigate each others’ work, ask students to share what worked well in a particular approach. Listen for and amplify any comments about the use of the words symmetric, skewed, bimodal, bell-shaped, and uniform to compare the two different displays. Then encourage students to make connections between the various ways to describe the different distributions. Revoice language students use to explain that the two different displays are equivalent. This will foster students’ meta-awareness and support constructive conversations as they compare and connect data displays that represent the same distribution.
Design Principle(s): Cultivate conversation; Maximize meta-awareness
Action and Expression: Internalize Executive Functions.
Provide students with a graphic organizer with the phrase “shapes of distributions” at the center, connecting to it all the related concepts mentioned during the discussion.
Supports accessibility for: Language; Organization


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