At the basis of all current theories of experiential learning, action-oriented learning, student activation and similarly related principles, lies one simple truth: Human beings learn better when they can act and discover new facts for themselves. The value of hands-on learning is no longer in any real doubt, and it is being increasingly implemented in various school types and grade levels. However, when it comes to teacher education, many countries still continue to educate overwhelmingly in the "academic" style -- students sitting in a lecture hall or seminar room and listening to (or, in the best case, discussing) ideas and theories of how to teach. Drawing on several small-scale studies of different school types and age groups in Germany, this paper will show the pressing need to implement hands-on learning during university teacher education. After all, we cannot expect teachers to teach what they do not know themselves.