This activity provides a simple introduction to the relationship between surface area and volume. It was intended for use before conducting an agar/phenolphthalein cell size lab, but may be used independently. Students begin by analyzing data, then they answer related questions and make predictions about lab outcomes. If a lab is not conducted, students may make predictions and then compare their expected results to the post-lab observations provided in the answer key. The final page of the handout asks students to apply what they have learned about the significance of increased surface area to other biological examples where it is important - including: the mitochondrion, intestinal epithelial cells, the human brain, and the desert hare.