Premature verbalization, and especially making students recreate facts of knowledge in a verbal way, results not only in memorizing, but it blocks the thinking process in general, and yet it is this very process that should lead to a proper understanding of physical concepts. In 1917 Smoluchowski [11], in his Manual for Self-Taught Learners, warned teachers against supplying children with definitions as long as they are still not ready for them. Physics uses abstract, closely interrelated concepts which have a precise meaning as abstracts, but - contrary to mathematical concepts - they have to be related to physical reality. When a concept gets verbalized too soon, while revealing its precise definition without properly substantiating its roots in physical reality, there is hardly any chance later on for a pupil to be able to perform a reverse operation, i.e. use the concept given to describe reality.