Sometimes it’s better to give students a data set rather than to collect their own.  With this activity, we needed to be sure that the data set would give us a standard deviation that was easy for students to compute with.  So when we are not having students collect relevant data, we still try to make it memorable with a theme.  This time we went with Back to the Future!

The goal of this activity was to give students an understanding of what a percentile and z-score tell us.  We are very focused on the students being able to accurately interpret, more so than on their ability to calculate.  This activity went really well.  Students were able to quickly figure out how many standard deviations away from the mean Marty and Biff’s scores were.  When the score was not a full standard deviation away, students had little issue finding the number of standard deviations as a decimal.  After they completed the page, we had them write in the margins that the percents they found in the first question were really percentiles.  We also wrote the z-scores in the margin for each of the questions they had answered.