30.

“To my first-year students: Yes, I always know when you didn’t do my math because you stayed up late playing Fortnite. You added me as a friend on Epic, so I see that. Also, the amount of homework not done when new Battle Passes come out is so coincidental.”

“To a specific first-year student: I support your desire to become a streamer, but editing videos should not keep you away from your homework for a whole week. Plus, your friends always rat you out when you stay home or skip class to make/edit those videos.

To all my high-schoolers: You’re dumb, but I love you. I’m not stupid. And while I know you cheat on your homework, I don’t care since it’s only worth 10% of your grade, and you’re forgoing the practice you can get before the test.

To my sixth-graders in math: Dear Lord, you make me cringe so hard I have to take ibuprofen some days.” 

—u/Thechadhimself

Source: https://www.buzzfeed.com/victoriavouloumanos/teachers-share-thing-wish-they-could-tell-students