This paper summarizes the thinking of 84 middle school mathematics students' about variability in three stochastics tasks that involve repeated trial. Differences in students' acknowledgment of variability were found, depending on whether the task was from a sampling environment, or a probability environment. Students tended to neglect variability in the probability environment. We conjecture that the way that probability is normally introduced to students is part of the cause of this phenomenon. (Contains 1 table.) [For complete proceedings, see ED500860.]