I know it's taught as if it's all proven, but I thought it was still a theory.
One of the key misunderstandings in this whole debate is the difference between the scientific and common use of the term "theory." In science, nothing is called a "theory" until it has been observed and supported by large amounts of evidence. For instance, we still have the "theory of gravity," which obviously isn't suggesting that we don't know for sure whether or not gravity exists. But when you and I say "
I have a theory," we mean a hypothesis. That one word has caused much of the confusion in this debate, which is unfortunate.
based on what I've read & what I studied in school, the theory of evolution is based on a little evidence & a whole lot of suppositions.
Actually the evidence is massive. We not only have fossil records for any number of species demonstrating genetic change over time, but we also have observed changes in current species. If you're honestly interested in getting past the summaries and down into the nitty-gritty details of evolutionary mechanisms,
Ontogeny & Phylogeny will tell you everything you wanted to know and then some. It's very, very technical, though, and one of the most difficult books I've ever read, so I'm not sure that's really something you'd be interested in, but feel free. Gould's
The Structure of Evolutionary Theory might give you a better sense of the background and justification for evolution, but it doesn't get down into the details the way that O&P does.
But back to the original point, evolution is backed up indisputable evidence and is accepted as scientific fact, unlike other debates on global warming, etc. That isn't to say that there aren't still disagreements, though, as evolutionary biologists have struggled to work out the precise mechanisms of how evolution works. So the question is no longer whether or not it exists (
and hasn't been for a century, really), but rather the specifics of how it does what it does. Also keep in mind that the origin of life is a somewhat separate although related question from how existing species change and differentiate over time (
sort of like how the Big Bang models are different from our understanding of modern physics).