Final-year students plan to sing the school song at Mt Albert Grammar School today after they were shut out of the school on their last day of regular classes.
About 130 of the school's 450 Year 13 students have signed up to a Facebook event planned after headmaster Pat Drumm called a special assembly yesterday to tell the students not to go to school today.
He said he wanted to let teachers attend today's Year 11 prizegiving, but also avoid "silly stuff" that has happened in past years on the last day of school, such as water fights and boys and girls swapping uniforms.
"Yes, it's also to send a pretty strong message that it's business as usual, and while it's a special day for the Year 11s, we don't need any of this silly stuff that can creep in at this time of the year," he said.
Year 13 student Ryan Naran said students were "outraged" by the last-minute decision, which meant they were unable to say goodbye to each other and to their teachers.