Avalon High
BookFilm I can understand why they made the changes. This is a Disney Channel original movie, and as such, they're going to make something suited to children. More importantly, it'll be at their level, so. Adults = the authority to combat, or in this case, the straight out villain, who works first to lure them into his trust circle. The "bad ass"/delinquent kid, who everyone suspects to be Mordred, is in fact, one of the good guys. (The adult teacher is Mordred.) A fellow kid is Merlin. (Whereas in the books, the teacher was Merlin.)
And while the girlfriend and best friend are still Guinevere and Lancelot, the football quarterback is not Arthur. The girl is. (Which, why, they take out the Uther/Igraine subplot mentioned below.) She's Lady of the Lake in the book. They changed her name from Elaine "Ellie" in the book to Allie in the film.
Not to mention, given the somewhat violent and darker tendencies of the book, most were wiped clean here, including the whole subplot with the book's "Arthur"'s father (Uther and Igraine). Leaving it with a more wholesome feeling. Not to mention, changing where it's set.
Which, all right. I get it. You wanted to create a family, friendly movie to empower children everywhere and make them believe they too can stand up for what is good and right, challenge authority, and that they too can make a difference.
I'm not sure I expected any different. Still, this is why I usually stick to the literary material.
Because nothing is that clean-cut, not even King Arthur.