Understanding randomness and its impact on student learning: lessons learned from building the Biology Concept Inventory (BCI)

Abstract

While researching student assumptions for the development of the Biology Concept Inventory (BCI; http://bioliteracy.net), we found that a wide class of student difficulties in molecular and evolutionary biology appears to be based on deep-seated, and often unaddressed, misconceptions about random processes. Data were based on more than 500 open-ended (primarily) college student responses, submitted online and analyzed through our Ed's Tools system, together with 28 thematic and think-aloud interviews with students, and the responses of students in introductory and advanced courses to questions on the BCI. Students believe that random processes are inefficient, whereas biological systems are very efficient. They are therefore quick to propose their own rational explanations for various processes, from diffusion to evolution. These rational explanations almost always make recourse to a driver, e.g., natural selection in evolution or concentration gradients in molecular biology, with the process taking place only when the driver is present, and ceasing when the driver is absent. For example, most students believe that diffusion only takes place when there is a concentration gradient, and that the mutational processes that change organisms occur only in response to natural selection pressures. An understanding that random processes take place all the time and can give rise to complex and often counterintuitive behaviors is almost totally absent. Even students who have had advanced or college physics, and can discuss diffusion correctly in that context, cannot make the transfer to biological processes, and passing through multiple conventional biology courses appears to have little effect on their underlying beliefs.

Figure 1.

Responses to questions 25 and 30 of the BCI show little change between students entering an introductory course (“pre-Introductory”) and entering the fourth course (“pre-Molecular Biology”) course in the MCDB/University of Colorado, Boulder, curriculum. There is an increase in correct response from pre- to postinstruction (arrows) associated with a transformed version of the introductory course (Biofundamentals) that exceeds the change associated with two (“pre-Cell Biology”) and three (“pre-Molecular Biology”) conventional courses, but whether this is reproducible or due to the fact that the course was taught by someone familiar with the BCI needs to be studied further.