Classroom management is a core component of teachers' professional knowledge (Voss et al., 2015). However, non-verbal classroom management components have rarely been considered as a focused component of classroom-management trainings, although some - mainly exploratory - studies indicate their relevance for successful classroom management (e.g., Kosinár, 2012a). Using a quasi-experimental pre-post design with two groups (N=40 master students enrolled in teacher training programs), it was investigated whether non-verbal classroom management knowledge can be taught using staged video vignettes. Furthermore, it was investigated whether learning can be improved when during the first of two presentations of each video the sound track is switched off in order - by reducing the unattended-speech effect (Salamé & Baddeley, 1982) - to be able to better focus on the non-vocal non-verbal communication elements. Results indicate an increase of nonverbal classroom management knowledge, but not of more general classroom management knowledge. However, switching off the soundtrack could not increase the effect.