To My 9 Or 10 Year Old Self:
It's not just you, and you're not full of shit. The 4th grade teacher really, truly, honestly is out to get you and is actively trying to fuck you over. Put up with it for the year, grit your teeth, speak up when she pulls her nonsense, and otherwise just shut up and do your work. On the last day of 4th grade, run up to her and kick her in her dusty old cooch as hard as you can as many times as you can. You're probably a yellow belt at this point if I remember right, so she'll definitely feel it. Whatever trouble you get in will be totally worth it, and you can rest easy knowing that the principle is totally on your side and will screw her out of thousands of dollars before the summer is out.
Also don't trust Matthew. He's a thieving little shit.
Sincerely, Your Older Self Who Still Wishes He'd Done It When He Had The Chance