Students at Kaitao Middle School want vandals to stay away from their school so they won't risk finding glass in their books or on the grass.
Yesterday morning teachers found eight windows had been smashed in the Wero Academy classrooms. It was the third time in three weeks the classrooms had been hit.
The last time one of the students was cut on his knee while playing outside, despite the groundsman clearing up the mess.
"We did a writing exercise after the last time," said Wero Academy leader Nat Jeeves-Edwards.
"It made them sad and angry that the school had to spend money on windows when it could be spent on something else. We want it to be a better learning experience but there's no budget for it.
"It's awful and really disheartening when you have to pick glass out of kids books. Class is supposed to be a safe place for them."
She said earlier this week she picked up a book and there was glass in it from the last time.
Yesterday, the teachers had to change their lesson plans as they had to wait for the rooms to be cleaned up and the windows boarded up. The glazier had no glass available and it would be next week before the rooms would be back to normal.
"I was quite upset," said Taryn Matthew-Sharp, 11.
"We don't want parents to let children out to break windows."
The incidents have been reported to Rotorua police.
"We're looking through some CCTV footage and we'll act on whatever leads we find," said Western Heights Neighbourhood Police Team supervisor Sergeant Steve Sutton.
"It's disappointing it's happened again. It affects the kids in that school. Someone out there will know who has done this."
Anyone who has any information should call Rotorua police on (07) 348 0099 or anonymously to Crimestoppers on 0800 555 111.