No. Tenure by estoppel provides that when a probationer is employed after the expiration of her probation she acquires tenure by operation of law. At the conclusion of her probationary term Barbara Files was advised that she would not obtain tenure but, at most, could expect an extension of her probation. She refused to accept the extension and when her probationary period expired she performed no “traditional teaching duties.” The Appellate Division, First Department, found that despite her being on payroll past her probationary period she not acquire tenure by estoppel since she did not perform these traditional teaching duties.