I need help teaching a 15 year old who i believe has the symptoms of schizophrenia Help

Has a "good kind person and a nasty person" (his words) and will identify them them and speak to them. Pictures all show a person split down the middle - one half smiling the other angry, with scars and always carrying a knike.For no apparent reason will throw table, chairs Sometimes talk when "good" Other time silent and sullen. Tries to get on with those he wants but will avoid others. has been excluded for violence so now in unit for the vulnerable, but not meeting his needs. Family history of vilence and mental health issues but ignore the behaviours of  their child, although aware of difficulyies will not act upon them. Deal with the violence and anger of the child at home with more anger and restraing etc