And the alternative is what? Good grades for effort? Self-esteem based education? Should we teach them that the flat earth theory is equally valid? Which of the following subjects do you have trouble with?
What do you think should be taught and why?
The Theory of Evolution is a champion of science on the cheap because it can be moulded to fit the evidence. Anyone can explain the universe apart from the intervention of an intelligence higher than that of man. Big deal!
"Natural Selection" is a reasonable explanation for the types and varieties of species available for observation in the present day. But it is only one of many possibilities and by no means the only contender as far as reason is concerned.
"Common Descent" is a reasonable assumption that, since the same building blocks are found in the bioshpere, they are all derived from a common, simpler life source. Talk about a leap of faith! Of course they are derived from a common source: God. The Creator of all things seen and unseen. The history of how and when the variety of life forms came about is a matter of FAITH for everyone living today. It is not available for "scientific" testing.
The "age of the earth"? What would satisfy your musings? Do you want an answer give-or-take-a-few-billion-years or down-to-the-nanosecond? Let me know when you figure out what "time" is.