Does the word "class" sound idiomatic in questions about grades/years at school, e.g.: What class are you in?
Is it acceptable to say: "I'm in (the) fourth class" (see here)? (I've added this question after placing my post here.)
It depends on the region, as rjpond said. In InE, we are now shifting to 'grade.' Which grade you are in? ~ Grade 7. As a kid, I had always answered 'Which class you are in?' ~ 7th Class!
Interestingly, in InE, 'years' are generally for the 'colleges' and not 'schools.' Say if you are in year 3, it would mean that you are in a college and in third year of some professional course.
In practice are all three: years, grades, and classes.