It depends. Contrary to popular belief, possession doesn't
always determine ownership.
Are the rights of kids limited in schools? For example, does
a teacher or administrator have to have a search warrant to search
an student?
No warrant is required to search a student. A school
official only needs a reasonable suspicion that the student has drugs
or a weapon in order to search.
What about locker searches?
Lockers in a school are considered the property of the school, not the
student, so school officials can search them at any time, even without
reasonable suspicions.
The student should be notified ahead of time and allowed to be present.
Are students allowed freedom of expression in school?
First Amendment Right of Speech is limited in a school in that it can't
be disruptive, obscene or advocate illegal activities.
So students can wear shirts with political messages?
A student in Michigan was suspended for wearing a shirt critical of
George Bush, but he won a lawsuit against the school.
Of course, the shirt can't be obscene or disruptive.
A student's right of privacy yields to the school's
need for safety, and expression of speech is generally allowed as long
as it is not disruptive.