I think this would be a chance to educate your child on fact vs opinion, but I really can't condone telling your child to act disrecpectfully toward the teacher, or have the kid going back to school with the attitude he/she is "smarter than most of the teachers anyway"...rather provide the child the correct information which, although studies are showing that Atkins is safe and effective, isn't conclusively proven to be the ONLY way to lose weight.

I agree that teachers shouldn't be presenting opinion as fact, but a lot of "fact" is really opinion depending on what side of the fence you're on. Teaching kids how to present an opposing viewpoint respectfully is an important lesson, IMHO.