In prior grades, students represented the distribution of a single statistical variable using dot plots, histograms, and box plots. In this lesson, students review those ways of displaying data and compare them with representing the relationship between two variables in a scatter plot. They aggregate data about hand span, arm span, and height for all students in the class, and use the data to create plots of a single variable as well as a scatter plot. (The data will be used again in later lessons, so should be kept in a spreadsheet or a permanent visual display in the classroom.) They notice that scatter plots can convey information about the relationship between two variables that representations of each variable separately do not reveal. They understand that every point in a scatter plot represents two measures of a single individual in the population.
In this lesson, students choose an appropriate way to display a data set (MP5) and see that the structure in a scatter plot can reveal information about a data set that is not visible in other representations (MP7).
- Create a representation of single-variable data using a box plot, histogram, or dot plot, and compare and contrast (orally) these representations with a scatter plot.
- Create a scatter plot from a table of data, and describe (orally and in writing) the trend of the data.
- Create a table of collected data, and explain (orally) how to organize the data.
Let’s collect and display some data about the class.
For the Gathering Data activity, each pair of students will need to measure some lengths in centimeters. Rulers, meter sticks, or tape measures would work for this purpose, so long as they are marked in centimeters.
At the end of the Gathering Data activity, students are instructed to add their data to a class table. It would be fine for students to record their individual data on the board for all to see. However, this data will be used again in a later lesson, so you need a way of preserving it for later. A useful mechanism might be to set up a shared spreadsheet that students access through a browser.
- I can draw a scatter plot to show data that has two paired variables.
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