Discussions about the what, the when and the how of teaching and learning in schools deal in German-speaking countries with the term "Lehrplan", while English-speaking countries discuss similar topics with the term "curriculum". Yet, these two terms are not just exchangeable terms in two different languages, but imply also two different styles of reasoning or two different modes of thinking. By the examples of a "Lehrplan" designed by Georg Kerschensteiner for the Munich school in 1899 and two different Lehrpläne for the elementary school in the Swiss canton of Zurich, one from 1905, the other just currently being implemented, the paper discusses the question, what is being studied, when the notion of "Lehrplan" defines the research focus. Against this backdrop the paper askes in a concluding chapter, what can be gained by guiding research by the Anglo-Saxon notion and tradition of "curriculum history" and if and how comparative research is possible, regarding the tight coupling of language and concepts.