Stilwell attached great importance to the teaching problem and put forward the historical task of studying scientific teaching theory from the perspective of reforming primary education, developing the role of ethnic schools and perfecting normal education. In the research of teaching theory, he attaches great importance to combining teaching practical experience with theoretical discussion. His series of expositions on teaching theory are based on rich practical experience and avoid vague dogma or speculative theoretical derivation. His teaching theory is mainly embodied in the book "German Teacher Education Guide".