Well established? It's simply not proven, period. You should only teach kids what you are 100% sure about, and when you're not than you have to honestly say that it's an assumption. Otherwise it is not teaching but conditioning.
> Evolution wasn't just made up, it was figured out from the evidence, just like gravity, electricity, chemistry, etc.
Gravity, electricity, etc.. are things you can prove, not the evolution of an ape into a human. I have no clue why so many people desire to believe that our ancestors were apes, I think it's rather pathetic, and most likely due to conditioning.