We believe that physics education has to meet today's requirement for a qualitative approach to Quantum Mechanics (QM) worldview. An effective answer to the corresponding instructional problem might allow the basic ideas of QM to be accessed at an early stage of physics education. This paper presents part of a project that aims at introducing a sufficient, simple, and relevant teaching approach towards QM into in-/preservice teacher education, i.e., at providing teachers with the indispensable scientific knowledge and epistemological base needed for a reform of science education along the aforementioned line. The investigation of teacher–learners' (t-ls') initial knowledge indicated that their main misconceptions appear to be the result of their pre-/inuniversity traditional instruction, which causes the overlapping/mix-up of the conceptual frameworks of Classical Physics (CP) and QM. Assuming that these misconceptions form by nature epistemological obstacles to the acquisition of QM knowledge, the educational strategy proposed here aims at leading t-ls to form a conceptual structure that includes CP and QM as two totally independent conceptual systems. Accepting, furthermore, that the complete distinction of these systems demands a radical reconstruction of t-ls' initial knowledge, we present here an instructional model that bases the required reconstruction on the juxtaposition of two models that constitute the signal point of twentieth century's “paradigm shift”: (a) Bohr's semiclassical atom model, and (b) the model of the atom accepted by modern physics theory. © 2003 Wiley Periodicals, Inc. Sci Ed87:257–280, 2003; Published online in Wiley InterScience ( DOI 10.1002/sce.10033