This module introduces activities that allow students to walk through the cell cycle and mitotic cell division processes. As part of the activities, students learn about and apply knowledge of chromosomal behavior to identify different stages of mitotic cell division in plant and animal cells. They also calculate and compare mitotic indices for normally dividing and cancerous cells. Students apply quantitative and statistical concepts such as sample size, mean, standard deviation, and standard error of the mean to discuss the impact of sample sizes on interpretation of biological data (i.e., normally dividing and tumor cells, in this case).