—Order unanimously affirmed with costs. Memorandum: Although defendant presented sufficient evidence to entitle it to summary judgment dismissing the complaint, plaintiff raised questions of fact concerning causation, notice and the existence of a dangerous condition on the stair in defendant’s school where plaintiff’s son fell, thereby warranting denial of defendant’s motion (see generally, Zuckerman v City of New York, 49 NY2d 557, 562).
Although slight differences in elevation have been held to be nonactionable (see, Morales v Riverbay Corp., 226 AD2d 271; see also, Julian v Sementelli, 234 AD2d 866; Guerrieri v Summa, 193 AD2d 647), the same cases also hold that even a trivial height differential may be actionable where the defect constitutes a trap, snare, or nuisance. Plaintiff submitted an affidavit of a licensed engineer whose opinion it was that the repair in the stair constituted a trap, notwithstanding its minimal height differential, because the depression in the front part of the repair was not readily observable under normal *1211conditions, thus creating a question of fact whether the defect constituted a dangerous condition.
The remaining contentions of defendant lack merit or are not preserved for our review (see, Walker v Huber, 254 AD2d 734; Matter of Rodgers v Crumb, 242 AD2d 874). (Appeal from Order of Supreme Court, Chautauqua County, Gerace, J.— Summary Judgment.) Present — Green, J. P., Pine, Wisner, Balio and Boehm, JJ.