could or would?!

Your sentence doesn't make much sense, but to answer your question, "would" denotes a stronger possibility than "could."

Here is the full sentences:

"The school I went to in the 1990s (in the nineteen-nineties) was very strict. If everyone got into a fight or trouble, her
parents would be notified immediately, and the school’s staff could/would temporarily expel her or only tell her off. Any fooling around and mockery in the class were strictly forbidden, and the teachers had to observed and reported ev

Mickey Mouse 8241the school’s staff could/would temporarily expel her

could - They had the power to expel a student. (Doesn't say that they always used that power.)
would - They expelled the student.

(Same contrast for "tell her off".)

Because of the choice "expel" or "tell off", could seems more appropriate to my ea

Mickey Mouse 8241If everyone got into a fight or trouble, [...]
the teachers had to observed and reported every student’s behavior and progress to the senior staff.

If anyone got into a fight ...
...the teachers had to observe and report ...

Thanks, According to the following linke, fight can be countable , could I ask you why you use 'fight' instead of 'a fight'?!
http://www.ldoceonline.com/dictionary/fight_2

It was a slip that I corrected - unfortunately not before you spotted it. Sorry.