Students can measure variability using standard deviations.
Students are paired and the reflexes of each partner are checked by dropping a ruler between the fingers of the other partner to determine how far the ruler falls before the partner catches it. The students are encouraged to outline procedures of the experiment before beginning it. Afterward they are also encouraged to discuss possible sources of variation that they observed during the activity. The goal of the competition is not only a low reaction time or distance, but also consistency, thus motivating the need for introducing standard deviation. Using the standard deviation to compare the variability of two distributions is covered.