Assessing undergraduate students’ understanding of carbon and oxygen in their world

Background/Question/Methods

At Bentley University undergraduates take 50% business courses and 50% arts and sciences courses, including a one-semester “intro” science.  In “Green Biology: Ecological and Botanical Connections,” I am particularly interested in helping non-science majors make connections between photosynthesis, respiration, biogeochemical cycles, food webs, macromolecules, climate change, and human influences, despite their many misconceptions. To connect all these topics together, I ask students on the first day of class where they would “look” to find oxygen and carbon. During the entire semester, I make no direct reference to those two questions, nor tell the students that they will be asked those questions again. On their last day of class, on the final exam, I ask the exact same questions: “Two elements that are especially important to life are oxygen and carbon.  If you wanted to find carbon atoms, where would you look?   Please list as many as you can.”  (same question for “…oxygen” ).” In Spring 2012 I introduced additional course activities (molecular models, Vernier probes, tetrazolium) intended to improve students’ understanding of the role of carbon and oxygen molecules in their world and in their understanding of where these elements are found and the ways in which they function.

Results/Conclusions

Not unexpectedly students are able to give more responses to these questions on the last day than the first day of class, but are still not as detailed as I would expect after a semester’s time. Also not surprisingly “air or atmosphere” and “water” are common answers for both of these elements. The most common new “last day” responses are related to macromolecules. Other responses seem to reveal some of the “plants photosynthesize, animals respire” misconception. Students give “plant/tree/forest/vegetation” responses for oxygen, but much less frequently relative to carbon. Conversely more references to “exhaling/respiration/carbon dioxide” are given for carbon and less frequently for oxygen.  Students also have a strong connection of carbon, but not oxygen, to “fire/charred/ash/burned/smoke.”  The tally of all responses reveals some other interesting misconceptions or lack of knowledge in college-age students, which is frustrating after trying to break those misunderstandings with new activities and more repetition.