Oral explanations (OE) by teachers are one of the most common forms of communication in the classroom to support students’ comprehension of subject-specific content. Thus, students have to deal with the language the teachers use in explanations. Research indicates that linguistic features (LF) of texts can influence students’ comprehension as they affect cognitive processes of text comprehension. While the importance of LF of texts has been addressed widely, to date, relatively little attention has been given to the influence of LF of teachers’ oral explanations on students’ comprehension. We aimed to investigate whether the linguistic design of teachers’ OE improves students’ comprehension. N = 102 German students (age: M = 14.04; 55.9% female) took part in the study. Students watched explanatory videos on the same content but with differing verbal complexity (simple/difficult). The two versions differed in their levels of cohesion and surface features at word and sentence level. After listening to the explanation, students’ comprehension was assessed. The results showed that the simpler version of the explanation was associated with significantly higher results in comprehension. The linguistic complexity of explanations affected students’ comprehension. The findings suggest that teachers should pay more attention to the linguistic complexity of OE.