Abstract: The traditional light speed measurement in college physics experiment course suffers from multiple uncertainties for comparing the light-beat signals in two different pathways. In this paper, an optimized method is developed by utilizing the cursor function of oscilloscope to measure the phase variation of only one light-beat signal, which achieves much better accuracy in a more operative way and can be easily applied to teaching practice of this experiment. It is found that the instructional design which incorporates this improved method will become more pedagogical to illustrate the essence of this measurement and help students develop critical thinking and spirits of exploration in scientific research. 

Key words:  light-beat, light speed measurement, teaching practice