This lab is a good introduction to diffusion. It demonstrates the concepts of semi-permeable membranes and diffusion for students. In consists of three parts. The first part is a teacher demonstration on semi-permeable membranes during which the students are asked to make observations and predictions. The second part is also a teacher demonstration, but deals with diffusion. Again the students are asked to make observations and predicitions. The last part is a student led experiment (mini) on diffusion. At the end of the three parts students are asked a series of questions to help them understand their observations.