Is it mandatory in the USA for the Constitution to be displayed in schools?

It's been a while since I've been inside a public school here in the US, but in all of the times that I ever have been in a public school here in the US, I've never, ever seen the Constitution displayed in one. Which isn't necessarily to say that none of them had one, but if they did, I sure never saw it. And I'm pretty sure the answer to your question is "no".