Seeing a student master a difficult concept is an example of an reward.

It is an example of extrinsic reward as this is a reward that is acquired after having to perform a task that has been difficult or has been a part of something big in accomplishing goals either in work or in school. It is considered to be an extrinsic reward because a teacher, having to see his or her student master a concept that is difficult, is already rewarding for them—which is referred to as an extrinsic reward.

sounds good to me mate!