Using DQCs to evaluate student retention of central biological concepts though a sequence of introductory biology courses

Background/Question/Methods

We collaborated on transforming our Introductory Biology (IB) courses based on recommendations of Vision and Change:  A Call to Action.  We had previously participated in a faculty development, NSF funded program, “Using DQCs to Improve IB Teaching.”  Use of DQCs (Diagnostic Question Clusters) motivated us to change our teaching style because we realized that our students are unable to apply scientific reasoning to questions about key biological concepts.  We were also interested in whether student retention of these concepts (post course completion) differed between traditional lecture versus active learning (AL) classrooms.   In Fall 2011, we tracked the learning behavior of biology students in two required courses.  Students in the first course “IB” were either in a traditional lecture or in an AL class in Fall 2011. The following semester (Spring 2012), students enrolled in “Ecology and Evolution (EE).”  A subset of these students (N=133) were assessed for retention on their understanding of the transfer of energy and matter in ecosystems; 32% of these students (N=43) had been in an IB AL class.  Students were given DQCs at the beginning of the semester in EE AL to determine retention of concepts covered in the previous semester. 

Results/Conclusions

We analyzed results from pre-test DCQs in EE.  We found that 10% of students who had not been in an AL IB class answered questions correctly about how plants obtain mass (through incorporation of CO2 from the atmosphere rather than absorption through roots), even though all students had covered photosynthesis and respiration for more than two hours in IB.   In comparison, 75% of students who had been enrolled in an IB AL class answered these questions correctly.  On the other hand, all students were still confused about whether matter (e.g., carbon) can be converted into energy. Preliminary data suggests that students engaged in-class activities (e.g., clickers, hand-outs, case studies) have higher retention of key biological concepts than students in traditional based lectures in IB.  However, some concepts need to be reinforced in sequential classes (e.g., EE) to effectively change their alternative conceptions about the flow of matter and energy in ecosystems.