Death by Osmosis: An interactive, investigative laboratory exercise

 

Tested Studies in Laboratory Teaching, 2000, Volume 21

Abstract

I devised this exercise to enhance interest and student involvement in what had become a rather routine laboratory demonstration of diffusion and osmosis. We begin the lab by having two student volunteers reading the short play "Death by Osmosis" in the roles of Sherlock Holmes and Dr. Watson. Student groups have materials sufficient to re-enact the murder weapon and a worksheet that challenges them to understand the processes involved. Different groups compare their hypotheses as to how and why the weapon works. After this discussion, to focus their efforts I read Holmes' soliloquy as I play a videotape showing the rubber-gloved hands of the murderer going through the necessary steps. This demonstrates the techniques they must follow in their own investigation. Such a videotape is easily made using a Flexcam, Vizcam, or similar desktop video camera. I enhanced the drama by overdubbing a haunting musical score (Phillip Glass' "Facades" from Glassworks). Now it's up to the students to solve the murder by reenactment of the weapon. The key question being, "how long will it take to tip over?" I have included the play and soliloquy, helpful figures, student worksheets, and notes to the instructor.

Keywords:  osmosis, diffusion

University of Nebraska, Lincoln (1999)