That's an awfully slippery slope. If said parent doesn't want their child to view a particular piece of art, but the other parents approve of it, what is that parent to do? Keep their child out of school for that day? That's not fair to that child. And I'm betting that the parent will not want to do that and will complain. Eventually, there are enough parents to force a change in curriculum. The other parents don't like this, but their concerns about their child missing out on the curriculum don't matter. Now, the children are getting less of an education because one parent thought that the statue of David was pornagraphic. If you think this is preposterous, I think you can find this happening all across the nation right now. We aren't that far from having public book burnings.