Because a scientific theory is different to a philosophy a philosophy is a cognitive model on the workings of life from a subjective perspective while a theory pertains to the accumilation of objective facts, models, evidence & data.

We learned in school that a scientific theory is something supported by fact but can't necessarily be proven fully yet.

Like the 'philosphy of general relativity?' Or, 'atomic philosophy?' Or 'The Big Bang philosophy?' What about 'germ philosophy' or the 'kinetic philosophy of gases?' Somehow it just doesn't sound right, and if a philosophy professor is teaching these courses, count me out. As Stephen Hawking said, 'philosohpy is dead.'

I suppose it is also a philosophy, but one based on strong theory and many-times-over obeserved facts.

While having a philosophy of reason and scientific methods can lead to reaching conclusions it does not explain any facts. Only a scientific theory can explain all the facts. It's not the Theory of Evolution, it is the theory of evolution by natural selection. It explains all the facts: the fossil record, genetics down to DNA, and real world observations. No philosophy can explain these things.

A scientific theory has been observed to be true many times, which is different from a mathematical theory that is proven. A scientific hypothesis is often shown mathematically before it is observed. For example the Higgs Boson was shown mathematically about 50 years before they were observed in an LHC experiment (Large Haydron Collider). One observation is not enough, two or more are reqired with a strong preference for more with the same results observed by different people. Often, results will be disputed by some scientists. However, almost all scientists agree on scientific theories.