In OR at high school?

[echelon]

Hi,

Is "in" or "at" correct in the following sentences? If both are correct, please say so and try to estimate which is more common.

"Teachers are more demanding at (OR in?) high schools than at (OR in?) primary schools."

"She was less happy at (OR in?) high school than at (OR in?) primary school."

Thank you.

[Tdol]

When thinking more of the system than the buildings, I'd use 'in', though others may have different suggestions. I'd use 'in' for the first and probably 'at' for the second, though this is less certain- it could have been a terrible place or maybe she disliked the courses.

[echelon]

it could have been a terrible place or maybe she disliked the courses.

Thank you. So if she meant "a terrible place" what should she use? At or In? What about if she dislikes the courses? At or In?