Motion and forces : a view of students' ideas in relation to physics teaching

This study concerns students' ideas about the existence or otherwise of forces in several dynamical situations involving moving objects and objects at rest. It aims to contribute to a better understanding of students' ideas about dynamics. It differs from previous research [a) in covering a wider-range among students and larger variation in taught Physics background. [b) in attempting to tap less verbal forms of evidence and [c) in attempting to avoid 'scientifism' in terms of the way to approach students and in terms of interpreting results. The empirical part of the study involved 338 students from seven different groups. Data was collected from the above sample. using a questionnaire to which responses were simply graphic indications of the directions of expected forces. and. if possible. the giving of names to these forces. in eight situations presented diagrammatically. In addition. data was collected from a sub-sample. by means of computer games using a screen 'object' obeying Newtonian Mechanics. in a frictional and a non-frictional 'environment'. under the control of the subject. Difficulties in interpreting the last kind of data led to the main study being focussed on the results of the questionnaire. Some results from the computer games are however presented. They are mainly concerned with students' performance when playing in a frictional versus non-frictional 'environment'. Results suggest a better students' performance when playing in a frictional 'environment'. Results obtained with the questionnaire concern: [a) differences between situations in patterns of expected directions. among students of the same group and between groups. Generally the results suggest the existence of common patterns among the students of the same group and systematic differences between patterns of groups with an increase in exposure to physics teaching. namely the attribution of new force directions [e.g. vertical and downwards. opposite to motion). despite the persistence of primitive ideas [e.g. a force along the motion); [b] names given to the different kinds of forces in various directions. Results include a difficulty found in naming forces which existed before teaching. They also give information about how scientific terms are assimilated. Interpretations of the results. mainly taken from a theory of Common Sense Reasoning about motions proposed by Ogborn (1985). seem to give them a reasonable explanation. Although requiring further investigation. this gives some support to claim that students' intuitive ideas about dynamics should be regarded [jJ as deriving from a rather general and coherent set of ideas. [ij] as less formalized in terms of the scientific world view and [iii] as having their origin mainly in actions on the world