Siegel enjoyed teaching, however, even elementary courses, and he published textbooks on the theory of numbers, celestial mechanics, and the theory of functions of several complex variables.
Siegel masaya pagtuturo, gayunman, kahit elementarya kurso, at siya nai-publish na aklat-aralin sa teorya ng mga numero, makalangit mechanics, at ang teorya ng pag-andar ng ilang mga kumplikadong variable.