  We describe the development of a course of quantum mechanics for secondary
school designed to address the challenges related to the revision of classical
knowledge, to the building of a well-organized knowledge structure on the
discipline, and to the development of a plausible picture of the quantum world.
The course is based on a systemic approach to conceptual change, which relies
on its analysis in the transition from classical to quantum mechanics, and
coordinates cognitive and epistemological aspects. We show how our approach
drives the derivation of design principles, how these principles guide the
development of the instructional sequence and of its strategies, how their
implementation requires the blending of different research perspectives and
learning systems. The first challenge is addressed through a path of revision
of classical concepts and constructs which leverages prior knowledge according
to the dynamics of each notion in theory change. The second by adopting a
framework that promotes the construction of a unifying picture of quantum
measurement across contexts. The third by designing the course around a
modelling process that engages students in epistemic practices of the
theoretical physicist, such as generating and/or running thought experiments,
and mathematical modelling in a purely theoretical setting. All is aimed to
help students accept the quantum description of the world as a plausible
product of their own inquiry. This process is assisted by the discussion of the
facets of the foundational debate that are triggered by each of the suggested
interpretive choices, with the goal to promote an awareness of its cultural
significance, of the limits the chosen stance, of the open issues. Data on the
cycles of refinement illustrate how a set of activities have been made
effective in addressing the challenges at a local level.
