Threshold concepts : challenging the way we think, teach and learn in biology

Students generally come to tertiary institutions with misconceptions of some of the key content and concepts in the disciplines they are studying. Their misconceptions commonly relate to conceptually difficult or troublesome content knowledge and can be: incomplete and contradictory; stable and highly resistant to change; and remain intact despite repeated instruction at successively higher levels perhaps reinforced by teachers and textbooks. Troublesome or difficult content knowledge in Biology includes cellular metabolic processes (for example, photosynthesis and respiration), cellular size and dimensionality (surface area to volume ratio), water movement (diffusion and osmosis) genetics (protein synthesis, cell division, DNA) evolution, homeostasis and equilibrium. We suggest that the threshold concepts of Meyer and Land, (2005) in biology are the ability to work with concepts and processes; energy, variation, randomness and probability, proportional reasoning, spatial and temporal scales, thinking at a submicroscopic level, and that these abilities, or lack thereof, underlie the difficult content or troublesome knowledge causing misconceptions. Threshold concepts thus provide a powerful heuristic to interrogate the cause of troublesome content knowledge in biology and to aid in the development of teaching interventions, to surface the tacit knowledge within the biology discipline.