In Ukraine you can’t get and A or B unless you get something for your teacher. They let you know what they need... could be a fridge if theirs is broken.... cost is $100 which is one month’s salary for a teacher there.
Here there is always a little gift for the teachers, in December for the holidays, and in June for the school year. I just give a little gift card to a store. It’s not a bribe for grades as my kids don’t get grades. (One is special needs at a hybrid school, and the other is only in preschool) it’s for appreciation. And last year my son had a terrible teacher and she got NOTHING.