Doing a physics lab on elastic material - Asked to list at least three sources of error in measurments and/or laboratory technique. I really do not understand what teacher is looking for?

sources of errors are basically what possible mistakes or what unusual circumstances could have caused the results of the experiment to not be accurate. so what you need to do is look at the materials or the experimental conditions involved in the lab and see what could have caused some form of faultiness in the reults or observations