Key Characteristics of the Scholarship of Teaching and Learning
This video is a great way to hear a variety of SoTL experts add nuance to a basic definition of SoTL.

The most basic definition of scholarship of teaching and learning that I use is that it is faculty undertaking systematic inquiry of learning in his or her own classroom. Every time a professor or a teacher teaches a course they're engaged in an experiment; the syllabus is a hypothesis that if I teach the class this way, if I teach this material in this order, and if students do these things, then I hypothesize that something will happen. Students will learn, they'll grow, they'll benefit, and that's how we play out every single time we teach.
What's missing is that final step of what an experimental mode would be, which is this is my hypothesis, this is the unfolding, and now I have to look very closely at the results and reexamine my hypothesis. So that loop closing happens always in some informal way.