and is replicated here as part of the SERC Pedagogic Service.
Course: Physical Geology Lab
We have a discussion on the scientific method, using an analog for volcanoes; either using an ultrasonic bath or the ever popular Mentos and cola eruptions (Baur and Baur, 2006; Wright et al., 2006). I incorporate the scientific method by utilizing different sodas (club soda, diet cola, regular cola and lemon-lime soda). As a class we brainstorm what we know about these sodas, either scientifically (i.e. diet cola is chemically sweetened and does not have sugar crystals) or anecdotal (i.e. a student proposes cola is more carbonated than lemon-lime soda). After we brainstorm, we develop a hypothesis predicting which soda will create the highest eruption, and then go outside and test it.
The hands-on experiment simulating volcanic eruptions helps students connect with the scientific method, but also relaxes them with their peers and instructor. Many of the students have seen the Mentos version of the experiment on the popular TV show 'Myth Busters' or on internet videos. Allowing them to get their hands dirty with something familiar, after explaining the scientific rationale, sets the stage for a productive, enjoyable semester!
I learned of this activity from Geoff Cook, currently (2009) a lecturer at the University of Rhode Island.
Student Handout (Microsoft Word 31kB Jan16 09)
Instructor's Guide (Microsoft Word 35kB Jan19 09)
Baur J.E. and Baur, M.B. (2006). The ultrasonic soda fountain: A dramatic demonstration of gas solubility in aqueous solutions. Journal of Chemical Education, 83:577-580.
Wright et al. (2006). Mentos and soda eruptions - lessons on explosive volcanic eruptions. http://nagt.org/nagt/programs/teachingmaterials/15949.html