I'll see u in/at school to discuss the details of the project.
Which is correct?

Question

Answer

Both are correct.

In this case it doesn't matter if you use "at" or "in".

Answer

两者都是正确的

"I'll see you at school" = when I get TO the location of school, I will see you there.

"I'll see you in school" = when I go INSIDE the school, I will see you there .

at school- i will see you there
in school- i will see you inside there 

i dont know, hope this helps.