Good indoor air quality is an essential prerequisite for a healthy learning environment. Scientific research has shown that there is a direct correlation between air quality and pupils’ ability to learn. For the same supply air volume flow, stratified ventilation systems lead to an improved quality of breathing air than mixing ventilation systems. The ventilation systems that work on the stratified ventilation principle are therefore particularly suitable for the ventilation of classrooms. The air flow characteristics of these systems in classrooms are, however, not thoroughly investigated. In the context of this work, the air flow parameters of various school ventilation systems with stratified ventilation for a typical classroom will be investigated by means of Computational Fluid Dynamics (CFD). For this purpose, centralized ventilation systems with different air outlets as well as decentralized systems are examined and compared regarding their ventilation effectiveness and thermal comfort.