HELP PLEASE BIOLOGY EMPERIMENT!?

One thing that you could do with Vegetable Oil/Olive Oil and the potatoes is coat them in the oil and then immerse them in lets say 500 mL of water. Then see what happens. IDK if this is correct, as I am making this up off of past experience...but the oil should rise to the top of the beaker due to its density. Hope this is the right level of difficulty that you are looking for...you could really go in depth with a lab ysis.