The theory of evolution is just a theory
The word theory means something different in science than it does in common usage. Theories are the result of a hypothesis, or educated suggestion, being tested and found to be consistent with observation. A theory coherently explains a large range of observations. It is in contrast to a law which simply expresses a regularity seen in observations without attempting to explain that regularity. Theories do not become laws. Laws are not somehow more certain than theories. Both are on equal footing in science.
There's no way life could have arisen from non-living chemicals/There's no way to get from the big bang to humans
Neither the origin of life nor the big bang is covered in the theory of evolution. Evolution only applies once life has begun. It makes no difference how life began.
The second law of thermodynamics makes evolution impossible
The second law of thermodynamics states that IN A CLOSED SYSTEM, entropy always increases. The earth is not a closed system. The earth receives energy from the sun. This release of energy from the surface of the sun at a temperature of 6000K to space at a temperature of ~3K represents an enormous increase in entropy. Therefore, even taking evolution into account, the entropy of the earth/sun system does indeed increase over time.
Creationism is just as valid a theory as evolution/Evolution is not really science
To qualify as a theory in science, an idea must explain observations in such a way as to be falsifiable. This means that it must predict something and finding that this prediction is not true would require abandonment or serious modification of the theory. Evolution meets this requirement. For example, evolution predicts that in billion year old rock layers, no fossils of modern humans will be found. It predicts that all organisms on earth will have nucleic acids as their genetic material. It predicts that it will be possible to observe changes in the genepool of organisms. All of these predictions have been borne out by observations. If any of them are not, then evolution would have to be seriously modified or abandoned. I am sure that someone with more knowledge of biology could provide many more such examples. Creationism, on the other hand, by its very nature can offer no such predictions. The most basic premise of creationism is that there is an omnipotent God who created the universe. By virtue of God's omnipotence, there is no possible observation that could falsify this premise. God could have made the universe appear any way He wanted it to appear.
Evolution has never been provenNeither has quantum theory, or relativity, or any other scientific theory or law. Science never offers proof, merely strong evidence for an idea. Evolution is backed by a large amount of observational evidence.
You are wrong about evolution having nothing to do with the origin of life.
But, if it does not, then the Creation theoy should certainly be taught!!!
If evolution does not explain how life began--only that it "chagned" after it began--then students need to hear the theory of how "life began." Sounds like intellegent design to me.