"at" or "in"?

[Dawood Usmani]

Hi teachers!
Which are correct?
1. We learn new things at school.
2. We learn new things in school.

3. We do a number of activities at school.
4. We do a number of activities in school.
Best regards!
Dawood

[Tdol]

Both pairs are fine IMO. I would 'at' to indicate the place and 'in' when thinking about the educational system, though others oculd use them differently.