standard_description: Develop a probability distribution for a random variable defined for a sample space in which probabilities are assigned empirically; find the expected value. For example, find a current data distribution on the number of TV sets per household in the United States, and calculate the expected number of sets per household. How many TV sets would you expect to find in 100 randomly selected households?
problem_activity: Narrative
The purpose of this activity is for students to analyze a line plot that represents lengths that are measured to the nearest half inch. They make observations and write statements about the data represented in the line plot, and then generate questions that could be answered with the line plot. When students recognize how organizing data helps to read the information and to answer questions, they learn that line plots are a powerful tool to present data (MP5).
Launch
Groups of 2
Display the list and line plot.
“The list and the line plot both show the heights of seedlings. A seedling is a young plant. Where have you seen seedlings before?” (At the park. In a garden.)
“Looking at the list, can we tell the height of the shortest seedling?” (Yes,
\(\frac{1}{2}\)
inch). “What about the tallest seedling?” (Yes, 5 inches)
“Draw a quick sketch of the shortest seedling and the tallest seedling at their actual heights. Use what you know about the length of an inch.”
1 minute: independent work time
“Share your sketches with your partner.”
“What else can we tell about the seedlings from looking at the list?” (Twenty-two seedlings were measured. There are two seedlings that are 3 inches tall.)
1 minute: partner discussion
Share responses.
Activity
“Now, take a close look at the line plot. Think about what information we can gather from the line plot and what questions it can help to answer.”
“Work with your partner to complete these problems.”
7–10 minutes: partner work time
Student Facing
heights of seedlings (in inches)
\(\frac{1}{ 2}\)
1
1
\(\frac{1}{ 2}\)
\(1\frac{1}{ 2}\)
\(2\frac{1}{ 2}\)
4
\(\frac{1}{ 2}\)
3
\(1\frac{1}{ 2}\)
5
\(1\frac{1}{2}\)
\(1\frac{1}{2}\)
\(2\frac{1}{2}\)
3
\(\frac{1}{2}\)
\(2\frac{1}{2}\)
\(1\frac{1}{2}\)
1
\(1\frac{1}{2}\)
4
2
[IMG]
[IMG]
Write 3 statements about the measurements represented in the line plot.
What questions could be answered more easily with the line plot than the list? Write at least 2 questions.
Student Response
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Activity Synthesis
Display the list and the line plot.
“How is the information displayed in the line plot different from that in the list?” (In the line plot, all the measurements that are the same length are together. The measurements go from smallest to largest along the bottom. In the line plot, we don’t keep writing the numbers over and over, we would just use an x for each measurement.)
“What were some questions that could be more easily answered with the line plot than the list?” (“How many seedlings were 3 inches tall?” because we could just count the x’s at 3 instead of searching through the list. “What’s the shortest seedling?” because we can find the x on the left end of the scale. “Which seedling height was the most common?” because we can see which number has the most x’s.)


aligns: no