This lab uses two different sizes of dialysis tubing to represent cellular and organelle membranes. Students design experiments in which they place solutions of iodine, starch, and glucose on different sides of a membrane. The movement of these materials is monitored with the use of indicator solutions. Students are given a list of tasks, a description of supplies and equipment, and some instructions on how to get started. They are then asked to design a set of experiments that will allow them to accomplish as many of the tasks as they can in the allotted time.