Yes the basic quantum mechanics chapter in Modern Physics isn't hard but we are talking about someone who just recently graduated from high school. And I'm not sure of the actual course it self but from what people say, it gets pretty complicated. I once thought that I could tackle a quantum mechanics book, not surprisingly, I failed. Everything looked like random gibberish symbols. So you do need a good background and intuition in certain things ; something that is likely to be taken for granted given that you probably weren't in the position to skip the prior classes.