Most schools have a Code of Conduct that you as a parent and your daughter as a student signed. There is nothing unconstitutional or discriminatory about having a policy and enforcing it. This question gets asked a lot. For example...
Here is a sample policy for a school nearby where I am (I am in Chicago, IL not TX) ...
High School XYZ: Cell phones must be turned off and kept out of sight during the school day. At the end of the school day, students may use cell phones throughout the building but must have teacher permission to use the cell phone in a teacher’s classroom. If a student wants to use a cell phone for medical, family, vocational, or other reasons, permission must be obtained from the building administration. A violation of this policy will lead to the cell phone being taken and your parents being notified to pay the fine outlined in the Code of Conduct.
Good luck.
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