Energy, Matter, and Organization: Connecting CO2 and pH with Exercise

We began class with a discussion of of the reading from yesterday.  The discussion focused on helping students understand how to read the questions, how to formulate a response, and the expectation of the quality and depth of thinking expected of a high school student of biology.  Notes from the white boards are pictured below:

After the discussion, students conducted an experiment designed to test the effect of exercise on the amount of carbon dioxide exhaled.  The experiment introduced students to the concept of cellular respiration (vocabulary they will learn soon) by studying the intersection of the cardiovascular and respiratory body systems.  Students measured pH as a surrogate measure of carbon dioxide output by exhaling into a straw placed in a cup of distilled water.  To measure pH, students used probeware connected to hand-held computers.  They measured the pH of the water before and after exercise, writing down their procedure and optimizing the procedure during the class period.  Students obtained data demonstrating a correlation between exhaled carbon dioxide and decreasing pH.

Students wishing to understand the chemistry behind our experiment should visit NOAA’s Ocean Acidification website.  The Smithsonian Institute also has an excellent collection of content explaining ocean acidification that includes some videos about how sea life is affected by increasing carbon dioxide in the atmosphere.