In this paper we present a project dedicated to the development of a didactical toolbox of material for teaching assistants (TAs) supervising exercise classes for non-physics majors at ETH Zurich. With our material we were able to support TAs in preparing high-quality exercise sessions for their class which go beyond direct instruction and activate students intellectually and emotionally. The materials are developed for 13 exercise sessions and are presented in the form of an eBook. The materials were immediately used by several TAs in dedicated focus groups. The positive feedback of students and TAs suggests that our material helped to activate and engage the students, enhancing their learning - even in the challenging setting of online teaching.