Evolution of an assessment project

We describe the evolution of a continuing project that started life as a study of students’ conceptions and reasoning patterns in elementary physics and morphed into a study of exam marking. The narrative structure of the paper reflects the evolutionary character of the project: aims and methods were not predetermined but developed as they interacted with each other. Our investigation began several years ago (Sharma, Millar, Smith and Sefton 2004) as a study of the way that students answer qualitative examination questions in physics and of what those answers tell us about patterns of conceptual understanding and reasoning. Specifically, we analysed answers to the following question: In a spaceship orbiting the earth, an astronaut tries to weigh himself on bathroom scales and finds that the scale indicates a zero reading. However, he is also aware that his mass hasn’t changed since he left the earth. Using physics principles, explain this apparent contradiction. The question was included in the final examination in 1998 for two alternative first-year first semester courses: a Fundamentals course for beginners and a Regular course for students who had done physics for the Higher School Certificate. We analysed a sample of 100 answers from each of the two courses