This activity guides students through the use of general data sets and central tendencies. As a class, two data sets are collected, one for both the height and ages of everyone in the classroom. The activity then discusses the concept of outliers. Mean, median, and mode are defined in terms of meanings and calculations. Then, each measure of central tendency is calculated for both of the classroom data sets (heights and ages), both with and without the outliers. The notes conclude with a question on whether outliers affect the mean or the median more and why.