Appeal from a judgment of the Supreme Court at Special Term, entered October 19,1978 in Albany County, which dismissed petitioner’s application, in a proceeding pursuant to CPLR article 78, to review a determination of the Commissioner of Education which denied the petitioner tenure by acquiescence. In September of 1973, the petitioner was appointed to a full-time employment as a probationary elementary teacher. Thereafter, she was appointed to a part-time (half days) learning disabilities position effective at the beginning of the 1975-1976 academic year. Petitioner served in that position until January of 1977 when the petitioner was appointed to a full-time position as an elementary reading teacher. At the end of the 1976-1977 school year, the petitioner’s employment was terminated, and she now seeks a determination that as a matter of law she had acquired tenure by estoppel because her employment continued beyond three years of service without termination. Upon her appeal to the Commissioner of Education and in the review by Special Term, the petitioner’s applications for relief have been denied and dismissed upon findings that her part-time service does not count toward tenure as a matter of law and further, that no estoppel could be invoked as to such service. The issue of whether or not the change in job titles affected her tenure area was not determined by the commissioner and is not now before the court for review. It has been held that part-time service does not constitute probationary service for the purpose of acquiring tenure (Matter of Rosenberg v Board of Educ., 51 AD2d 551; Matter of Nyboe v Allen, 7 AD2d 822). Nevertheless, it has been held that the grant of tenure and/or the grant of tenure/probation credit for part-time employment is not violative of any public policy or statute (Matter of Schlosser v Board of Educ., 62 AD2d 207, affd 47 NY2d 811). In the Nyboe case (supra), the court did not construe the statutes as prohibiting probation credit for part-time service, but limited its finding to the conclusion that it could not be said that the Commissioner of Education was arbitrary and capricious in his construction of the statutory requirements. In Nyboe the teacher petitioner was originally hired on a part-time basis and it does not appear that at any. point in her six years of employment there was a full-time appointment or any appointment to a probationary period. In the present case, it is undisputed that the petitioner was appointed to a probationary period effective with the commencement of the 1973-1974 school year and, accordingly, the issue presented as to the effect of subsequent part-time service is *979distinguishable in fact and principle from Nyboe. The question of the inviolability of the requirement of three years of full-time service was considered in the case of Matter of Weinbrown v Board of Educ. (28 NY2d 474), and it was held that the statute did not prohibit the earlier grant of tenure; and upon acceptance by a teacher it could not thereafter be rescinded unilaterally by a board of education. In the Weinbrown case, the court expressly noted that while requiring a stated number of years of service, former section 3013 of the Education Law expressly provided for the grant of tenure by a board of education upon earlier recommendation by a superintendent. In Matter of Matthews v Nyquist (67 AD2d 790), this court considered the effect of appointing a full-time teacher to a probationary period and then at the end of the three-year period giving her a defective notice of denial of tenure. It held that continuing her as a part-time teacher would not defeat a claim to tenure by estoppel in that she served beyond the three-year period of probation. The same result was previously reached in Matter of Dwyer v Board of Educ. (61 AD2d 859) in spite of the fact that the petitioner was duly notified of the denial of tenure prior to continuing her services as a part-time teacher. In the Schlosser case, the Court of Appeals explicitly noted that it was not determining the applicability of the statutory scheme of tenure to part-time teachers. For the acquisition of tenure, former section 3013 of the Education Law, in effect when the petitioner was terminated from her employment, required solely that the petitioner be appointed, and in keeping with the requirements of the Nyboe case the appointment herein was to a full-time position. The statute does not differentiate as to part-time service and full-time service and, accordingly, the commissioner erred in relying upon the Nyboe case to deny probationary service for the part-time service. The analogy of tenure by estoppel arising from any service at the end of the probationary period in the Matthews and Dwyer cases requires the conclusion that as a matter of law the change to part-time service does not interrupt a duly established probationary period. Although there has been no showing of any sound or rational basis for finding that a conversion to part-time status from a full-time probationary status would affect the accumulation of probationary/tenure credit, the matter must be remitted for further consideration by the commissioner of whether or not the particular service of the petitioner can all be credited to the same tenure area. The issue of area tenure was raised in the pleadings before the commissioner, but was not considered in reaching his decision. It should be further noted that the issue of section 3813 of the Education Law was not properly raised as a defense in this proceeding and Special Term erred in its sua sponte introduction of that matter (Matter of Schlosser v Board of Educ., 47 NY2d 811, supra). Judgment reversed, on the law and the facts, without costs, determination annulled, and matter remitted to Special Term for remittal to the commissioner for further proceedings not inconsistent herewith. Kane, Staley, Jr., and Herlihy, JJ., concur.