We talk about the mature of learning and how it means that we should have some level of discomfort. We also talk about how we have experienced this in our lives and some ways to determine if our discomfort is from ourselves, the instructor, or the material.
The article mentioned is this one:
https://edu.rsc.org/opinion/in-pursuit-of-discomfort/4010955.article#.XiZV6zCYLiM.twitter