My very first day teaching an undergraduate class, I opened the discussion up for questions, and a student asked me why I wanted to teach. I felt myself flush, and inelegantly explained that I had really enjoyed my work as a TA, tutor, and mentor for Coursera learners. It took most of that first semester for me to better put into words the excitement of distilling what is special about a discipline, and then working out how to help students see it. I am certain each of us creates knowledge for ourselves as we learn, building on the scaffolding of our prior world view, until we have a working knowledge of a new content area. It is deeply rewarding to foster and witness that process as students engage in it.