A HANDS-ON LAB TO HELP INTRODUCTORY STUDENTS GRASP THE CARBON CYCLE

Developing a lab exercise for an introductory class so that it is interesting for your students can be very challenging. This is especially the case if you teach non-science majors enrolled in the course to fulfill a general education requirement. An effective way of achieving this is to provide hands on activities that encourage group collaboration and constructivist problem solving skills. We have developed a lab exercise that can be used in a variety of courses in either geological or biological disciplines that uses biological substrates acting as carbon sinks (either trees or bivalve shells). This is a major concept that students need to learn in order to understand global climate change and increasing atmospheric CO₂ levels. For this exercise, students are asked to develop a relationship between a biometric measurement (e.g., shell height or tree diameter) and the carbon stored in the substrate. We ran this aspect of the lab as a whole class activity. Next, the students were asked to make calculations regarding the amount of carbon currently stored in the living specimens of the particular species they are working on (run either as a small group or individual exercise) based on given information concerning shell (or tree) density and total surface area where the species is present. The students are then provided with data on how much carbon a typical automobile emits per kilometer and how this relates to the carbon in their biological CO₂ sink. Finally, they are asked to relate a large geological feature, such as the cliffs of Dover (which are made almost entirely from phytoplankton shells) or to a large biological feature, such as a forest in the vicinity of the school, to the exercise they just completed. This lab exposes the students to many levels of the carbon cycle. Moreover it reinforces their computer and reasoning skills. We ran this lab in an introductory level environmental geology class using common hard clam shells. The students clearly enjoyed the lab and were amazed at how many clams it took to absorb the CO₂ emitted while driving a very short distance!