Our investigations of conceptual understanding of biology have led to the formulation of a matrix of threshold concepts for the discipline (Ross et al, 2010), of which the creation and testing of a hypothesis is a key component. Previous studies of this threshold concept (Taylor, 2009; Taylor and Meyer, 2010) confirm that it is fundamental to thinking and reasoning across the sciences, and that the complexity of the concept requires detailed elucidation if we are to design teaching experiences which track students in this extended liminal space (Lawson, 2000; Oh, 2010; Pederson, 2011).
We employed two approaches to identifying the dimensions of thinking about hypotheses and their testing: 1) a generic question “what is a hypothesis”, and 2) a scenario question requiring students to write a relevant hypothesis for a field investigation. Both questions were given to 900 incoming undergraduate science students in an introductory biology course. Responses to the first question yielded 72 item stems, which covered a broad range of conceptions of a hypothesis, and could be further categorized into 13 groupings. The responses to the scenario question were analysed phenomenographically and provided 7 categories of understanding which were broadly hierarchical.
Despite this concept being a fundamental area for study throughout the high school science syllabus, a significant proportion of the cohort demonstrated unsophisticated conceptions of the structure of the hypothesis. There were distinct commonalities in the dimensions of problem areas, namely the conception and delineation of variables, relationships between variables, the construction of a testable statement, and the language used to describe the hypothesis.
Further refinement of our approaches has led to the development of a diagnostic psychometric instrument about hypotheses, and the creation of a range of scenario questions, currently in use in high school investigations and in longitudinal surveys of students in biology-related degree programs.