Bad Behavior in school

First time poster and on mobile so i apologize for any mistakes. Background info: Myself(21F) and my husband(23m) recently got gaurdianship of his 5 year old half brother. We have had him since January of this year. We have no kids of our own. In the beginning he was very erratic and out of control, but now at about 2 months of having him at home we are able to calm him down and stop his violent behavior right away, he even does chores! But his behavior at school seems to be more violent than ever... The school has even tried changing his schedule, and more. We have him on a month long waitlist to see a behavioral management specialist/therapist and CYFD has been no help whatsoever. Any advice on talking to a 5 year old about his behavior? We got mad/angry in the beginning due to no experience with a child of our own, but are trying the "I'm not mad at you" and "its okay, but..." and that had not worked for lectures about school. He is so nice and understanding at home now but i get daily incident reports from his school. I have no idea what to do. Any advice would be appreciated! via /r/Parenting https://ift.tt/2ExQBuX