1. Using plural pronouns:
* "All students must bring their permission slips if they want to participate."
2. Using the singular "they":
* "Every student must bring their permission slip if they want to participate."
* While this is becoming increasingly accepted, some people still find it grammatically incorrect.
3. Rewording to avoid pronouns:
* "Students who want to participate must bring permission slips."
* "To participate, all students must bring a permission slip."
4. Using a specific noun instead of a pronoun:
* "Each student must bring his or her permission slip if he or she wants to participate."
* While technically grammatically correct, this can become repetitive and awkward.
Which option you choose will depend on your preference and context.