In 1975, the United States Supreme Court upheld a National Labor Relations Board (NLRB) decision that employees have a right to union representation at investigatory interviews. These rights have become known as the Weingarten Rights.
If you're meeting with the administration, formally or informally, remember that anything you say could be used in a disciplinary action. If you believe a conversation might lead to disciplinary action, halt the discussion, invoke your Weingarten rights, and contact an AEA representative (linked below). A union representative will attend the meeting to ensure that you are questioned fairly, that notes are taken of the event, and to be there to support you.
Administration is under NO OBLIGATION to inform you of your Weingarten Rights. If you do not invoke your rights, you will not have access to them.