What are the variables for this science experiment?

[Dragonwardude]

http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p006.shtml?fave=no&isb=c2lkOjEsaWE6Rm9vZFNjaSxwOjQscmlkOjc1NjE5NzE&from=TSW

please help me. Thank you!