Subject: why does sugar dissolve in vegetable oil and salt does not?

I am homeschooling. I'm playing around with kitchen chemistry, I discovered 
that sugar will dissolve in vegetable oil but salt will not. Why is that? I 
figured that it was because both were from the plant kingdom, so I tried to 
dissolve sugar in olive oil, but it did not. It just coagulated; neither did 
yeast dissolve in the oil. What is going on and how can I validate the answer? 
Thanks...I read the information on denaturization, and it went way over my 
head. Can I have a simpler explaination and a way to observe other ingredients 
in my kitchen to show my kids? They range from 5th grade to 9th grade. The 9th 
grader is studying chemical bonding, but I just don't get how to connect the 
two together. Thank you for your help. 

Re: why does sugar dissolve in vegetable oil and salt does not?