This document discusses the nature of teaching practice and the need for professional training of teachers. It argues that teaching is "unnatural work" that requires specialized skills not developed through everyday experiences. While helping others learn is common, professional classroom teaching requires skills like intentionally structuring learning opportunities, assessing student understanding, and maintaining attention on students' perspectives - which do not come naturally. The work of teaching is complex, involving integrating knowledge, skills, and judgment to advance student learning. Well-designed, practice-focused training is needed to help people learn to do this work effectively and improve significantly on what can be learned through experience alone.