Keeping All Students Safe Act This bill prohibits the use of seclusion and limits the use of physical restraint in schools and Head Start programs that receive federal funding. Specifically, the bill prohibits the use of seclusion, which is the involuntary confinement of a student alone in a room or area from which the student is physically prevented from leaving. The term does not include a time out, which may involve separating the student from others in a non-locked setting. The bill prohibits the use of mechanical or chemical restraints or physical restraints that restrict breathing or are life threatening. The bill outlines the requirements for the use of physical restraint, including that the student's behavior must pose an imminent danger of serious physical injury to the student or other individual. Each state must ensure that a sufficient number of program personnel are trained and certified by a state-approved crisis intervention training program. Additionally, each program must establish procedures to follow after an incident involving physical restraint. Further, the bill establishes enforcement provisions, including a private right of action for a student who has been subjected to unlawful seclusion or restraint. The Department of Education and the Department of Health and Human Services must withhold payments from a program for unlawful seclusion or restraint. Finally, the bill requires each state educational agency (SEA) to establish, implement, and enforce policies and procedures required by the bill. It also creates a grant program to assist SEAs with these activities.