question:

students are asked to find the acceleration due to gravity on earth. students drop objects from a height and measure the time it takes to reach the ground. from this procedure the acceleration is calculated. unfortunately, students in the class got very inconsistent results. identify possible reasons for the inconsistent results.

Most likely the students are using a crude measurement of time, like a stopwatch. They would get the best results with a scientific apparatus that uses a computer and optical sensors. Even recording their dropped objects with a video camera and analyzing the video would give more consistent results. Results will also vary greatly if different people are taking the time measures instead of one person making all measurements.