1. The problem statement, all variables and given/known data If all students start with the same amount of 10,000 x g supernatant, and after different groups of students have done their 40-65% ammonium sulfate cut, their results tend to vary greatly. What are likely reasons for this variance? 2. Relevant equations None. 3. The attempt at a solution I was thinking that if everyone started out with the same amount of supernatant and if the ammonium sulfate needed to be measured out based on the volume of supernatant present, maybe it's possible that different amounts of ammonium sulfate could have been measured out in the beginning before it was added to the supernatant. Otherwise maybe that it's possible that the rate of speed at which the amount of ammonium sulfate added to the supernatant may have been different which could impact the rate at which the supernatant becomes saturated? Any other input on this would be great.