In humans, the transfer of respiratory gases between the atmosphere and living cells depends on their diffusion between lungs, blood, and cells, as well as their advective transport by breathing and circulation of blood. Fick’s law helps us measure and understand gas transfer from a perspective of diffusion. Fick’s principle helps us do the same from a perspective of advection.

The tertiary teaching of Fick’s law and principle is generally done in isolation from each other. Fick’s law is generally introduced to life science students in the first year of a tertiary program, whereas later in a program students might be introduced to Fick’s principle when, for example, they study cardiovascular and/or respiratory physiology and learn about pulmonary gas exchange. Fick’s law and principle are represented by different equations, each with their own complexities, and can be challenging to teach and learn. In particular, there is a significant challenge in learning about gas transfer across the blood-gas barrier given the complexities associated with pulmonary vascular anatomy and different gas solubilities in alveoli and blood.

The pedagogical value of exploring connections between Fick’s law and principle as applied to pulmonary gas exchange is unclear. Both Fick equations can be related to core principles of physiology such as “mass balance,” “flow-down gradients,” “movement of substances,” “interdependence,” and “integration” (1–3). There are mathematical and graphical demonstrations of interdependence between Fick’s law and principle as they apply to oxygen transfer (V̇o₂) across the blood-gas barrier (4–6), but their teaching utility is unclear. When teaching Fick equations in relation to pulmonary gas exchange, there will be a need to negotiate challenges of poor numeracy and quantitative skills among students (7–10). As yet, there appears to have been no attempt to develop an effective way of aligning Fick’s law and principle to help students learn connections between them and there is little understanding of the pedagogical value of doing so.