The Berlin concept was tested in a controlled study (Lichtfeldt 1992). A trial group of 11 basic and advanced courses in Berlin, taught according to the Berlin concept, was compared with a control group of 14 classes taught in the conventional way according to the Berlin curriculum. Lichtfeldt collected data as follows:
1. Before and after the quantum physics lessons, students completed questionnaires on their ideas about quantum physics. The answers were scored according to whether they correctly reflected quantum mechanical ideas.
2. Interviews were conducted in some classes to gain deeper insight into the topics covered by the questionnaires.
To assess the teaching concept, the ideas of the students in the trial group determined in this way were compared with those of the control group.
Lichtfeldt found that after the lessons, the students in the trial group answered significantly differently. The students were classified according to whether their answers showed no, slight, satisfactory or complete conceptions in the sense of quantum mechanics. About 20 % of the students in the trial group could be assigned to the category “complete conceptions”; there were no such students in the control group. “Satisfactory conceptions” were shown by 47 % of the trial group and 2 % of the control group.
Lichtfeldt attributes this advantage of the trial group to the sequence of content, which differs from the conventional curricula. He sees the decisive factor in starting quantum physics with electrons: “Starting the teaching unit with electrons picks the students up at their mechanistic level of conception, and the presentation of the novel behavior of electrons forces them to think about possible explanations.”