at school vs. in school

[Achi15]

hello there
first thanks much for helping me for my poor English and all the lessons I am getting from you

I have one Question about ( In and At)
where is the different between In and At, when can I use In or At.

Example: At the park.
In the park

At school
In school

[Vmahdizadeh]

i think "at" used for time and in for place!! yeah?

[Torsten]

Please read at school vs. in school.

Best regards,
Torsten

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