You shouldn't mess around in your classes.
John is in a Biology class.
John wants to alleviate his boredom.
John asks to go to the bathroom, where he splashes some water on his face, stretches his legs and re-focuses his attention.
John makes a paper airplane and throws it over to his friend Bob.
John comes back to class with a bit more energy, ready to take some notes.
The teacher notices John's behavior and gives him extra work to do after class.