There you go, now your screen is just garbled to your teacher, of course all this does is make it so that the program is non responsive so that doesnt...
Using this simple method you can stop those annoying teachers from spying on what you are doing from their computer without using any hotkeys or anything of that matter.
Step 1: Work out what your school computers have
In this step you need to find out what your school has on your computer that it uses to track what you do. My school uses a program called lanschool, it has a teacher and student application running on the either of the computers respectively.