Complex sentence: After an incident where Noah--in defense of Kevin--slams a bully named Jason's head into a locker repeatedly, he is called into Vicky's office and discovers that Noah was kicked out of his previous school for disorderly conduct.
Split into simpler sentences: After an incident where Noah--in defense of Kevin--slams a bully named Jason's head into a locker repeatedly, he is called into Vicky's office. She discovers that Noah was kicked out of his previous school for disorderly conduct.