Write 1-2 questions you have about grading

I’m not sure I understand this question but if it do; one question I have about grading is why when you get one zero it brings your grade down a ton, but when you get 5 A’s your grade doesn’t budget? Another question I have is how do they put grades together, like how do they calculate it?

1- why are teachers so strict
2-why do teachers talk
:)

Goodest should be best