Building a picture of students' conceptions of wave- and particle-like properties of quantum entities

Quantum mechanics is considered conceptually to be a demanding topic due to the classically counterintuitive nature of its basic concepts and entities. A study is carried out where a picture of students' conceptual understanding of quantum entities (quantum `particles') is constructed. This is done by analysing students' qualitative problem solving. The problem used as a research tool in this study is based on an example of the gradual formation of interference pattern for either low intensity light or electron beam passing through a two-slit system. It is suggested that students' conceptions can be described with four distinct models of `description categories', which are (a) quasi-classical (particle ontology based), (b) trajectory based, (c) statistical (probabilistic) and (d) quasi-quantum models. In most cases the responses are dominated by classical pictures and trajectory based reasoning, described by categories (a) and (b). In just a few cases, the responses give evidence of the formation of new quantum ontology. In these cases, the students' responses can be described adequately by a combination of categories (c) and (d).