Subject: What is a experimental variable and control of experiment described below?

We were asked to conduct an experiment to prove a hypothesis about air in an 
egg.  One theory is that the animal insilde has enough air enclosed in the 
eggshell.  My hypothesis is If there are microscopic holes in an eggshell then 
air bubbles will be seen coming from the egg submerged in water.  Will the 
variable be water temp., time in water, or various eggs?  Would the control be 
leaving the egg in water for a certain amt. of time, temp of water or using a 
certain egg?  Mom, dad, cousin, and friend have all given advise.  What is the 
best choice?

Re: What is a experimental variable and control of experiment described below?