These behaviors are not, unfortunately, completely unheard of in young children.  In your case it sounds like your child is, at least in part, testing to see how the adults in his life will react. I'm hoping that your son's actions resulted in developmentally appropriate consequences--some important privilege being taken away for a modest period of time, maybe three days for the first offense and a week for the second. Another possibility is that your child is experiencing some learning issues, especially if misbehavior occurs mainly in school. "Forgetting" homework, if it becomes a pattern, may suggest difficulty with either the work or with the organization skills needed to get that task done. That doesn't mean there should not be a consequence for the inappropriate behaviors, just that you have to look past the immediate situation and try to see if the bigger picture is something more than just being either oppositional or mischievous.  Most kids are desperate to please their parents and these behaviors may have been misguided attempts to do this. I don't think you should assume that these behaviors represent significant moral failures. My choice would be normal (though misguided) child behavior to try to stay out of trouble, possibly complicated by learning or attention problems if there is an ongoing pattern of these behaviors. Keep in touch with the school and ask for guidance about when and whether a systematic assessment of the situation is needed.      

Dr. Jeanne Funk
education.com clinical child psychology expert