Learning how to teach is a skill typically learned by doing. For more than 30 years, I struggled, through trial and error, to improve the help I gave my students. After switching my research effort from nuclear physics to physics education more than a dozen years ago, I have studied (and developed) theories of learning and education. The focus of my research has been on understanding my students' cognitive (how they think) and epistemological (how they know) behaviors. This workshop presentation outlines my theoretical model and how the day-to-day activities of my teaching practice have changed as a result of my looking at teaching from a theoretical perspective. The workshop includes demonstration exercises of some new pedagogical methods developed using this perspective.