This classic activity/lab is one of my favorites and helps to illustrate a concept that is often difficult to students - the idea behind, and being able to explain, the relationship of surface area to volume in a cell. This updated version offers guided pre-lab questions and procedure as well as post-lab synthesis questions. The integration of calculations for surface area and volume are a necessary part of the lab and help students to explain the concept of cell size.
Preparation is easy and the bright pink color change is exciting for students to observe. This lab can also be used for different preparations of agar cubes with any color change reagents. Placement of this lab can be anytime during a unit on cells and pre-lab discussion or homework can focus on where the teacher is as to content. A discussion of the cell membrane and diffusion are part of this lab as well and offer a good introduction to membranes and transport.