This link is great because it does a nice job of wording the amendments in terms easily understood. Freedom of religion is one of the classical fundamental human rights.
This link is takes you directly to the History Channel website, which holds articles, videos and picture regarding the First Amendment.
A short video answering a question on the civics exam about Freedom of Religion.
This link discusses the Free Exercise Clause that refers to the section of the First Amendment: Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.