Teaching principles first leads to large gains in student understanding of carbon-transforming processes

Background/Question/Methods

Many college students are able to articulate the principles of conservation of matter and energy, yet few are able to use these principles as a tool for reasoning about ecological scenarios.  We are particularly interested in student understanding of carbon-transforming processes in socio-ecological systems, including cellular and organismal metabolism, ecosystem energetics and carbon cycling, carbon sequestration, and combustion of fossil fuels. We wondered if explicit instruction in using these principles as the basis for reasoning would improve students’ ability to reason about these processes.

We developed an instructional model to help students develop principle-based reasoning skills in a course for non-science majors in an elementary education program.  Our model included using principles first and foremost in all curricular instruction (ecology, physiology, geology, climatology) and using principles as a reasoning tool.  It also included three specific teaching strategies - a physical model of matter and energy, the use of precise language, and concrete examples drawn from students’ lives.  

Diagnostic Question Clusters (DQCs) concerning transformations of energy and matter were used to assess whether students apply these principles when asked to explain carbon transforming processes.  We compared pre-post gains in performance on DQCs for faculty using our model (n=6) to those using other instructional methods (n=7 faculty teaching science majors).  Item response theory was used to estimate the level of performance.

Results/Conclusions

While pre-post gains in student proficiency were significant for both groups (p<0.0001), the gain in the model group was greater leading to a larger effect size for the Model group (1.506 v. 0.310).  The results are striking given the limited science background of these students (two general education courses) compared with the science majors.  Interviews conducted with a subset of these students confirmed their ability to apply principle-based reasoning when presented with new examples of biological processes (e.g., a rotting tree).  Many students reported that the use of the physical models of matter (paper clips represented atoms) and energy (paper strips represented energy units) was instrumental in their developing an understanding of conservation of matter and energy (always the same number of paper clips and paper strips before and after any physical or chemical change).  The models were also useful in helping students visually remember that matter and energy are not inter-converted (“paper clips can’t become paper strips”).  Our results suggest that college students (even non-science majors) are capable of incorporating principle-based reasoning as a powerful tool in understanding carbon-transforming processes.