What are the variables in doing a science experiment to prove photosynthesis

My science experiment is to put a leaf in a flask, sit test tube upside down on top of the flask, leave for however many hours, get a wooden splint ready on a bunsen and perform the pop test to show there is oxygen and prove photosynthesis. Now i have 2 questions to answer.... What are the variables in the experiment? and Which variables were controlled? Please help, would be greatly appreciated. :)

you aren't comparing two different systems so there is no IV

the DV is oxygen levels or presence of oxygen

the controls are mass of leaf, test tube size, time, wooden splint (what species is the wood? ex.pine), bunsen heat, etc