Next week in my English class, my teacher is going to start teaching us some Middle English. Is there anything important I should know about it, like pronunciation and such? Thanks!

Phonologically, I believe the only differences from Modern English are the inclusion and lack of certain vowels, e.g., /y/ and /œ/, the presence of vowel length, the presence of /x/, and it's possible that the /r/ be trilled. Not entirely sure, depends on your teacher, I guess.

Vocabulary wise, this was the beginning of the mass importation of French (Latinate) words so they may look different and may have more common, for the time, germanic counterparts. e.g. sight instead of vision.

Grammatically, I believe there are more inflections. Not Sure

Oh yeah, also the presence of /ç/ which was lost in Modern English. (But it reappears in modern English, although I only consistently pronounce it in the word human, /çjumɛn/.)

Correct me if I'm wrong, but I think you forgot the GVS.