Addendum:
As I mentioned earlier, many of the students I taught were under the age of 18. While in my class, and, thus, under my care, I had the responsibility to keep them safe from harm, but, under Russian law, that was the extent of my proxy rights and responsibilities in the absence of the students' parents. As the teacher, I had the right to require students to not use their cell phones, and the most I could do was to deprive them of the right to use it during class by having it put in a box if they absolutely couldn't control themselves, but it was returned immediately at the end of class. If I had dared held it beyond the end of class or demanded some kind of payment for its return, I would have been arrested and charged with criminal theft of property.
I honestly can't understand how schools in the U.S. are allowed to get away with this. Is criminal law regarding theft, or the rights of schools as parent in proxy, really that different between Russia and the United States?