My son has a hard time focusing in class and I don’t know why.

There could be many reasons why your son is distracted in class. Maybe he’s sitting by a noisy partner, or perhaps he can’t see the board and loses interest. You might want to get his eyes checked and make sure that he is fine. His teacher should be able to give you further insight as to his behavior in class and a discussion with him/her should be in order. Good Luck.