I agree with your teacher.
Student or Learner
Original sentence: it is common for children in Australia to have drama lessons in high school.
A teacher commented that 'high school' is a concept and abstraction here and hence there is no need to pluralize it. Is this correct? I thought it should be in high schools. thanks
I'd like to ask a question here.
Does this 'in high school' have a similar meaning to 'in high school education'?
I would say yes to that, TZF.
I'd take it to mean "while they are in high school", which is similar to Mike's suggestion. Compare:
"Many people catch infections in hospital."
"You can study history at university."
"People do a lot of things in bed."
The plurals are all correct too, but not colloquial.