First ... recall that the IDIOTS who want this nonsense taught in schools are the SAME IDIOTS who hate public school teachers. What kind of moron wants a teacher that they HATE to teach their kid religion? After all, as a crazy right wing parent, you have spent years INDOCTRINATING that child within a very narrow community. When you open this discussion up within a school setting, your children will be exposed to a broader world view.
Second ... the creationists have spent years trying to find tiny gaps in evolution, and then using those to claim ... "see, evolution doesn't work". If you try to teach creationism in school, that same examination of "gaps" can be placed on creationism. And Creationism doesn't just have gaps ... it has huge chasms and canyons which can not be bridged.
And so, if you place them next to each other ... compare what they predict, the absolute silliness of creationism will become apparent.
Sure, the crazies will attempt to teach it in a particular manner, but they won't be able to do that state wide ... I bet they can't even do it completely for a single school district or even single school.
Parents would engage, much like what happened in Dover PA a few years back ... a few nuts took over a local school board, the parents flipped out ... and a judge tossed Creationism OUT.
If it does show up in class, lots of the indoctrinated kids will see the creationism that their parents have taught them ripped to shreds. They won't be able to not question it.