Grade quesion help

Hi!
My name is George I am a 2grade. my teacher Madame Gazelle grade me best friend Dannys essay A, but give me a D, it’s no fair, only because Danny think that’s his hardest work, and I think it’s quite easy for me.

please help me , I hope this is the right group to join. BTW, me another friend Rebecca, her teacher give everyone F no matter whut, she sad: Other class A is me class F. Whut does that meaning?