I thought about blacking out the lights in the elevators but the entire ceiling is a light

Use the tape to "write" blocky letters on 3 backpacks: 1, 2, & 4. They will panic about backpack #3.
But you might get arrested for that one if you get caught.

Eh nah.
Also I’m Australian we ain’t intense about bomb scares.

Get some raw shrimp and tape them to the underside of a table.

I like the raw shrimp idea, horrible smell that will annoy everyone but wont cause any actual damage.

I found another elevator which had smaller lights. I’ll post a pic if it’s not taken down yet

Goddamit it got taken down.

Tape off a stairway

Put a huge X on a bathroom stall door

Kidnap someone and tape their mouth and hands, before murdering them.

Haha, i mean.. uh.. tape a doorway so nobody can get in... yeah...

This is amusing
Let us know how it goes

Find a black surface and put strips of black tape on it. Everyone will think it's just a black surface but you'll know it actually has tape on it.

Speed around the school and put tape over as many classrooms as possible, then walk into a roandom room, give to someone,before going to lesson

*Classroom doors*