In the student's first week, it's alleged Northwood said "give me one week with the boy and I'll get rid of him".
Northwood denies the allegation.
In the last two weeks of term, Northwood allegedly provoked the student into threatening to punch him.
The deputy principal said Northwood admitted the provocation to her, saying "I set that up".
Northwood told the tribunal the allegation wasn't true.
The second charge he faced was for breaching his ethical responsibilities as a teacher, particularly in relation to how he treated his colleagues.
In 2014, the Manunui School Board of Trustees chairwoman hand-delivered a letter to Northwood's home, to inform him of complaints against him.
The chairwoman told the tribunal that when Northwood read the letter he began pacing the room, becoming "angry and abusive".
She wasn't sure of the exact words used, but she remembered him saying "you're a fat and ugly person", "you'll pay for this", and "you're a puppet".
In a later email that was sent to several colleagues and the Ministry of Education, he referred to a NZSTA adviser as "that fat lady in the red costume from NZSTA".
The tribunal found Northwood's behaviour amounted to serious misconduct.
It ruled that the allegations Northwood tried to provoke a student into punching him were unfounded.
However, it found he did try to compromise the student's relationship with his mentor, by telling the mentor the student was "a liar, a bully, and a thief".
The tribunal's decision included a criticism of Northwood for having a lack of insight or remorse, which it said put students and colleagues at risk.
Northwood was censured, his teacher registration cancelled, and was ordered to pay 50 per cent of the costs of the disciplinary process.