Kerikeri High School is due to reopen to all students on Monday after a fire destroyed a toilet block and damaged three classrooms.
The blaze, which started about 2.20pm on Wednesday, is still being investigated.
All 1500 students stayed home on Thursday on the advice of the Ministry of Education while a thorough damage assessment was carried out.
Senior students, in Years 11-13, went back on Friday.
In an email to parents principal Elizabeth Forgie said seniors had come back early because it was close to the end of their school year when every day counted.