I'm in university, and last semester I failed to turn in a paper that got less than an 85, and most got 90+. I know how to write.
So how do you expand on your ideas? consider implications outside of the direct answer. Consider not just the 'because', but the 'why'.
For instance: Essay question: Was Hitler a good thing for Germany?
You can very easily answer that question in one sentence, either way. Yes, he was a good thing for Germany because he improved their administration. No, He wasn't a good thing for Germany because of the holocaust. However, there's a TON to consider there. You could brainstorm a ton of different points to argue either side. 3 points would be enough to give you your basic 5 paragraph form essay.
However, if you got 9 points, you could organize them into 3 big subtopics, and write '5 paragraph essays' for each set of subtopics; the paper would be much longer.
Do you use word 2007? If you do, I can take one of my papers from last year and annotate it to show you how I organized and formed a bigger essay. I wrote a 9 page essay on a certain topic in Bolshevik Russia, and I only had 2 major points. Now, those two points I reinforced with 3-4 pieces of evidence each, but it goes to show that you don't really need a lot of stuff to go on to expand something into something really big.
If you were to give us the topic, I might be able to suggest where you might start expanding; I'm a writing tutor at the university level, and so while I won't give you your essay topics and points, I might be able to help you get started.