This paper investigates differences in students having various scores when designing controlled experiments in two types of scientific inquiry tasks (a fair test and an exhaustive test). We measure temporal features of preparation time and execution time, which reflect respectively the process of question understanding and answer planning and that of executing the control-of-variables strategy in answer formulation. We also measure mean execution time per answering event to reflect the efficiency of answering events. Results show that: in the fair test, the full score students showed less execution time than the lowest score ones; in the exhaustive test, the full score students showed more execution time than the lowest score ones; but in both tests, the high-performing students had less mean execution time than the low-performing ones. These results reveal that despite test differences, students who appropriately apply the control-of-variables strategy in these tests are more goal-directed and efficient in planning and executing response strategies than those who fail to do so. This study provides process-based features and large-scale evidence of scientific inquiry practice in in educational assessment. [For the full proceedings, see ED607784.]