Personal experience and the experience of colleagues. I spent 11 years in the undergraduate/graduate system both learning and teaching. It's also something yo

Personal experience and the experience of colleagues. I spent 11 years in the undergraduate/graduate system both learning and teaching. It's also something you can learn if you ever have to look for work in academia. It's very rare that anyone cares about your teaching credentials. Typically undergraduate education is at the bottom of a professor's concerns. First is research/publications/funding. Next are graduate students and their research. Undergraduate teaching is an 'in the time left' activity.