Threshold concepts are fundamental understandings that sit at the heart of a body of knowledge. Students need to 'get' them in order for core disciplinary knowledge to make sense. They are like a portal, opening up a new and previously inaccessible way of thinking. They can be challenging, troubling and finally transformative. They matter in curriculum design as there are places in learning where students get 'stuck". Here curricula can be designed to help them take the steps towards really 'getting' the understanding they need to know, which is core to the discipline.
Examples of threshold concepts from broader discipline areas include:
- 'opportunity cost' in Economics
- 'gravity' in Physics and Engineering
- 'depreciation' in Accounting, and
- 'deconstruction for text analysis' in English literature.
Temperature Gradient: An example of a threshold concept
Through a simple experiment, a trainee chef reflects on the relationship between heat transfer and temperature gradient, both important physics concepts for the chef's art:
- Two identical cups of tea are poured
- To cool down one as quickly as possible, milk is added to Cup 1
- After waiting a few minutes, milk is added to Cup 2
- The chef is asked to reflect which cup would be cooler, Cup 1 or Cup 2?
What do you think?
Intuitively, you would think the first cup will be cooler but it is the second. In the initial stages of cooling, Cup 2 is hotter than Cup 1 (with the milk already in it) therefore loses more heat. In technical terms, this is because of the steeper temperature gradient.
Through this simple learning experience, the trainee chef comes to reflect on the concept of heat transfer as a function of temperature gradient. Once this principle is understood, trainee chefs will shift their attention from ingredients to selecting appropriate pots and pans. This kind of shift in understanding a subject marks an important initiation into any subject culture.