Here's an updated lab covering cell surface area, diffusion, and the efficiency of small cells. It walks biology students through surface area and volume calculations. Students place agar-phenolphthalein blocks in sodium hydroxide and watch the diffusion take place. The bright pink color allows them to see how small cells diffuse quicker. The analysis questions review membrane concepts covered in an earlier unit. This is a great classroom lab that includes data collection, critical analysis, mathematics in biology, and inquiry.