Final answer:
The best method to inform athletes and their guardians about football risks is to send a letter with an informational consent form to ensure informed consent and document the communication.
Step-by-step explanation:
Informing all athletes and their parents and/or guardians of the potential risks and dangers associated with high school football is best addressed through the communication technique of sending an informational letter and consent form to the parents and/or guardians of all athletes. This method ensures that all relevant parties are made aware of the risks and benefits and are provided with written documentation, which aids in giving appropriate consent. It is a reliable approach to fulfill the responsibility of athletic trainers and school administrators in guaranteeing the safety of participants and ensuring informed consent.