I am a middle school science teacher and want to model a science fair project for my students. Specifically I want to investigate using a vent in the top of the handle of a gallon milk jug to alleviate the air glugging when pouring and achieve faster pouring rates. So far I believe the following factors are in play (or would at least seem to be worthy of consideration as possible variables):
Initial angle of tilt.
Opening size, both the pouring opening and the vent opening.
Stiffness of the container.
Viscosity of the liquid.
At this point in time I intend to make assumptions that the last three are relatively constant given that I will be using standard plastic milk jugs and water from the tap. I do not believe the changes in atmospheric pressure will be significant but I do think that will make for a good thinking/discussion point for my students.
I am particularly interested in the variables aspect of experimentation as I know from experience this is something my 6th graders are not good with. I am mostly looking for the obvious things, factors that even with their limited experimental and life experiences they can relate to.
Any input would be much appreciated!