  We investigate the difficulties that undergraduate students in quantum
mechanics courses have in transferring learning from previous courses or within
the same course from one context to another by administering written tests and
conducting individual interviews. Quantum mechanics is abstract and its
paradigm is very different from the classical one. A good grasp of the
principles of quantum mechanics requires creating and organizing a knowledge
structure consistent with the quantum postulates. Previously learned concepts
such as the principle of superposition and probability can be useful in quantum
mechanics if students are given opportunity to build associations between new
and prior knowledge. We also discuss the need for better alignment between
quantum mechanics and modern physics courses taken previously because
semi-classical models can impede internalization of the quantum paradigm in
more advanced courses.
