I always thought that of all the amendments to the US Constitution, the first one was both the most memorable and the easiest to understand: You can say what you like, outside of the famous “shouting fire” example, and the government can’t stop you. Easy. A toddler could get it.
(My mother taught civics/law and justice for 25 years, and I assure you that when your humble author was a toddler he understood the First Amendment.)