Same to us, different to them: Numeric computation versus symbolic representation

Data from nearly 900 students was used to measure differences in performance on numeric and symbolic questions. Symbolic versions of two numeric kinematics questions were created by replacing numeric values with symbolic variables. The mean score on one of the numeric questions was 50% higher than the analogous symbolic question. An analysis of the written work revealed that the primary identifiable error when working on the symbolic problems was a confusion of the meaning of the variables. The paper concludes with a discussion of possible theoretical explanations and plans for future follow-up studies.