How do you say school finishes at 315 in French?

The most natural way to say "school finishes at 3:15" in French is:

L'école finit à 15h15.

Here's why:

* L'école = The school

* finit = finishes (verb "finir" in the third person singular)

* à = at

* 15h15 = 3:15 (French time format uses a 24-hour clock)

You could also say:

* On finit les cours à 15h15. (We finish classes at 3:15)

* Les cours se terminent à 15h15. (Classes end at 3:15)

These options emphasize the end of classes rather than the school itself.