Education Technology

Find Line of Best Fit

Published on 08/26/2010

Activity Overview

Students make a scatter plot of heart rate versus age data and draw lines of best fit using three different methods—by hand, using the upper and lower quartiles, and using the handheld’s regression feature.

Key Steps

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    In this activity, students will create a scatter plot representing resting heart rates versus age.

    They graph vertical and horizontal lines to show Q1 and Q3 for both the ages and the heart rates.

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    Students will create a scatter plot of the data. They attempt two versions to find the three lines of best fit, as well as horizontal and vertical lines marking the upper and lower quartiles of the data.


    For the first method of finding a line of best fit, students place a moveable line on the graph and adjust it by hand to make it as close to all of the data points as possible.

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    For the second method of finding a line of best fit, students can use the One-Variable Statistics command to find the upper and lower quartiles of each data set.


    They then draw horizontal and vertical lines to mark the quartiles on the scatter plot. Using point-slope form, they should write the equation of a diagonal line that intersects two of the corners of the rectangle formed by these lines and follows the trend of the data.