well in my 13 years of experience in the system about 2/3 of the teachers are mediocre to complete garbage.
it's different at every school I guess, but I recently realized that when I started elementry school the teachers at mine were mostly older and strict but by the time I was in grade 8 they had all been replaced by women who just had kids and never shut the fuck up about it and just dump 4 hours of homework on kids every night and expect them to learn from it. it ruins childhoods.
in highschool it isn't as bad but there are still a good amount of fuckwad teachers who either have no idea what they are doing or are just complete dicks.
my english teacher was throwing around the word 'upwards' and she didn't know what it meant.
she told us we needed an upwards of 10 pages of notes and everybody was like wow that's a lot of fuckin notes, at which point we had to explain to her that upwards meant more than.