Before engaging in the evolution side-debate, I want to clarify something: teaching someone about Creationism does not make them less ignorant. It takes a few seconds to inform someone: "Creationism is the belief that a higher power of some unfathomable kind made life as we know it." Once that is done, it reveals nothing new about the world or how the world works. It sheds no light on something that before was beyond imagination or explains why something is or does. Creationism is very much the end rather than the beginning. To say that a cow has four legs because God made it so tells us nothing about why the cow has four legs. For that reason, Creationism has no place in a school. There are other reasons that have already been mentioned that I agree with and some I don't, but I don't feel like they need to be addressed again.
With that done, onto evolution. First of all, I want to criticise the various mentions of "random chance" because that's very much not what evolution is. Let us separate evolution from natural selection. Evolution is focused on the changing of species into new species. Natural selection is the dynamic filtering of the gene pool where some chance is involved, but there is also bias, with genes that best build survival machines (ie animals) being more likely to survive and continue their existence in the pool.
Evolution is something that has been observed via selective breeding. There is no way to doubt that evolution can occur because selective breeding can produce animals that differ greatly from their ancestors in a small amount of generations. Natural selection is harder to directly observe, because it works on a longer time frame since it doesn't have an intelligence to decide what factors make good survival machines. So, if evidence is wanted, one must look at species that are similar yet in different environments and check if the differences between them match the differences in environment, such as Darwin's finches. I'll leave it at that without going onto the other evidence supporting as that's easily found at Wikipedia.
To address Tara's earlier point regarding the non-mutation of bacteria to a more advanced form of life, I feel like I can offer only layman possibilities as I'm not formerly educated in the area. The first suggestion is that bacteria bred by humans is in infinitely different conditions to those that gave rise to the complex ancestors. The second is that time frames for life before bones or hard substances in general is unknown and hard to estimate simply due to the lack of fossils or similar to date it, thus it is unknown how long ancestral bacteria had at their disposal to produce complexity - even saying this though, we have been growing bacteria for but a thousand years at a very generous estimate, while ancestral bacteria could easily have many millennia and the entire world as their Petri-dish. The third is that it may have been the case that a large supply of raw materials led to vast diversity and that diversity let different strains form mutually beneficial partnerships of sorts that eventually coalesced into a "single" life form that paved the way for more complex life. I could go on, but I feel like I'm already walking on thin academic ice.
Intelligent design is a very real possibility, but not for explaining life on earth. As Tara hinted at, gene splicing is possible and that can/will/may allow new life forms to be made to a specification. It may not be on the level of creating miniature cows that makes chocolate milk, but it fits the bill for a life form being produced by a conscious mind with a specific purpose or purposes.
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