How student-constructed models reveal content understanding

Background/Question/Methods

Pedagogical approaches that engage students in the active construction and evaluation of conceptual models may support students’ acquisition of both deep content knowledge and systems thinking skills, both of which are critical skills in contemporary biology. As students create conceptual models of biological systems, they make choices about which system components or structures to include (e.g., DNA, decomposer), how these structures relate to one another (e.g., the relationship between decomposers and the atmosphere) and, in the process, reveal content understanding.

We asked whether an iterative, model‐based pedagogy could help students gain systems thinking skills and content understanding in introductory biology. Here, we present results from two major content areas typical of introductory biology: principles of genetics and ecosystem ecology. A component of genetics instruction included student construction of conceptual models of gene expression. We coded student-generated models for correctness of relationships among structures and paid particular attention to connections between allele and related genetics concepts. Ecosystem ecology instruction focused on students’ ability to build models of the movement of matter through ecosystems. In this instance, we coded student-generated models for the presence, absence, and correctness of key pools and fluxes.

Results/Conclusions

Students were able to construct models on a comprehensive final exam in which 70% correctly connected allele to gene. Approximately 1/3 of students connected allele to nucleotide or to protein but with varying levels of correctness and 27% of students connected allele to phenotype, but few of these connections were completely correct. These results demonstrate the difficulty in understanding and representing allele, a common core concept in genetics instruction, and underscore a need for explicit instruction that fully integrates allele into the broader genetics curriculum.

Student-constructed models of carbon cycling revealed students’ propensity to identify macroscopic carbon pools (e.g., plants, consumers) and difficulty in representing microscopic pools (e.g., decomposers). Students were proficient identifying visible fluxes (e.g., consumption) yet more than half of students consistently omitted respiration and photosynthesis; indeed, the number of students including either process decreased from a quiz to the final exam, significantly so for photosynthesis.

An iterative, model-based pedagogy refocuses the undergraduate, introductory biology classroom away from rote memorization to relationships between and among biological concepts. Indeed, these results demonstrate the insight models provide into student understanding of key biological relationships and underscore the potential of a model-based pedagogy.