Why would a 5-year-old boy who is normally very well behaved suddenly start acting up at school home public etc?

Usually children of this age that start acting up have a good reason and at this age they just "act out" and don't know why. I just saw a program tonight on "bullying" and was shocked that even 4 - 5 year olds can experience these feelings from their peers. Name calling, pushing, shoving, excluding them from playing within their groups, sharing toys. If your son is in pre-school it's best to talk to the teacher and find out what is going on. Don't accuse, ask for her advice. Perhaps she will suggest that you stand outside, look in through the classroom window to see how your child is interacting with his peers or even the teacher. If you are home-schooling your child, then you have to be sure you balance his play time with his peers because he won't be in a classroom to do that. Parents divorcing can affect children of this age as well or the loss of a parent. Another problem is ADD (attention deficit disorder) or hypersensitivity. I would see your family doctor for an evaluation just to rule this out. Also have your son's ears and eyes checked out. My nephew was in Grade 1 and doing poorly, and getting into scraps with a few of the kids who were calling him stupid. His parents thought he was the one at fault, but it turned out from the keen eyes of my mother (his grandmother) that he couldn't hear! He needed to have tubes put into his ears for a few months, and the problem was solved. Also families who constantly argue (not blaming you here) can also disrupt children of any age. 4 - 5 year old only know to act out anger in these situations I have suggested. Good luck God Bless Marcy