Many, although not a majority, of Americans believe in Creationism. It would be unfair to teach something that they don't believe in to be truth. Even better, evolution should be cut out from biology textbooks. Even if someone proposes that nationwide, schools will present both sides, it is very easy for teachers to be biased and share their bias with their students
There is just as much scientific evidence for creationism as there is for evolution and so creationism should be included in the conversation as well. Essentially both are theories put forth to explain where everything came from, why should one be excluded? Kids should be given the facts about where scientists believe we came from.
Students learning about the origins of life should be shown all plausible theories. These theories should be presented with supporting evidence for all views and should be presented equally. If parents of a student wish to teach their own version of how life originated they should be allowed the option of having their children not attend when these lessons are being conducted.
The idea that all alternative ideas should be taught is ridiculous. Should we teach children that 9/11 and the moon landing were government conspiracies? Of course not. Education is not opinion . . . Facts are facts. Also, education is not about making a large percent of people happy about having their biases included.