Memorandum: Plaintiff, a 17 year old, was injured when he used a chair to launch himself into the air to dunk a basketball during an open gym period. By submitting evidentiary proof in admissible form that defendant violated its written policy of supervision, plaintiff raised an issue of fact sufficient to withstand defendant’s motion for summary judgment. Whether that breach of duty was a proximate cause of plaintiff’s injury is a matter for jury determination (see, Benitez v New York City Bd. of Educ., 73 NY2d 650, 656-658; Derdiarian v Felix Contr. Corp., 51 NY2d 308, 314-315, rearg denied 52 NY2d 784).
All concur except Lawton, J. P., who dissents and votes to reverse in the following Memorandum.