A ‘conceptual gateway’ into a subject.
Threshold concepts open a door into a new way of thinking about something and therefore enhance the ability of learners to master their subjects. For example, in Physics the concept of ‘gravity’ might be used as a threshold concept. An object in motion might be described (such as a rolling ball) which will not slow down unless an external force of some kind (such as gravity or friction) affects the motion of the object.