Subject: Oil separates from water, but does it sink or float?

I am a fifth grade teacher and I have a decoration on my desk - one 
of those things you flip over and blue and red oil drip through holes 
down through water and sink to the bottom.  One of my students asked 
me why the oil sinks to the bottom because whenever he sees pictures 
of an oil spill in the ocean, the oil floats on the top.  I told him 
I wasn't sure and that I would find out for him.  I would appreciate 
you help.  Also, I hope I can get through to get the answer, because 
when I try different parts of you website, it sometimes says 
"Unsupported Web Version"  and I can't go any further.  If at all 
possible, please e-mail me the answer.  Thank you, Karen

Re: Oil separates from water, but does it sink or float?