No one argued they don't have rights. I don't see anyone in this entire thread making that argument. What ghost are you shadow boxing with?

Until and unless you have a rebuttal to the concept of In loco parentis, you may as well just shut up, unless your aim is to continue making a fool of yourself. This is broadly applied through the compulsory levels of education in the US, and while it doesn't automatically invalidate students' rights, it does give schools broad authority to limit those rights in the place of students' guardians, who are unable to constantly be present and assent to the school's every decision, and upper courts have already held that this is sufficient in cases where there exists a compelling interest to do so in order to further the school's basic purpose as an educational institution.

This is entirely in line with the way minors cannot sign legally binding contracts without their parents co-signing, in most instances. Similarly, see curfew laws and local rules aimed at minors, they're inability to legally consent until they reach the age of majority, and any other number of situations in which the rights of minors are temporarily curtailed in the name of their own best interests. The notion that minors have the same full civil rights as adults do in all circumstances is entirely devoid of any basis in reality. Indeed, even adults can have their rights abrogated in certain circumstances. You can argue whether it's right or wrong that someone can lose their right to vote or to bear arms as a consequence of a felony conviction, but absent new laws (such as some of the efforts recently to restore the right to vote to felons in several states), this is a fairly settled matter in law. To act as though this doesn't occur with full legal sanction in schools on a regular basis in the US is disingenuous, at the very least.