Last year I was expelled for something I did outside of school and nowhere near the school it was simlpy a prank on the internet that the teachers saw Is it illegal for a teacher to punish you for something you did outside of school

The answer to your question may depend on whether you were enrolled in a public or private school.

         The authority of public schools to expel students for off-campus Internet activities is significantly limited by the First Amendment.  Courts that have considered this question have consistently ruled that the school may take disciplinary action for off-campus Internet activity only if the Internet activity threatened the school's staff or students or otherwise substantially disrupted the school's operations or activities.  Internet activities that merely embarrass or annoy, or that are distasteful, are generally beyond the reach of the public school that the student attends.

        On the other hand, private schools are not obligated to honor the First Amendment rights of their students.  Accordingly, they have much more latitude to decide whether a student's misconduct, regardless of whether it occurs at school or off-campus, warrants expulsion.