The plaintiffs appeal from a decision of the State Board of Education (State board) denying their application to provide home education for six-year-old Justin Peirce. They claim that the State board made erroneous evidentiary findings and failed to enforce certain due process procedures. We affirm in part, reverse in part, and remand.
On May 1, 1980, the plaintiffs, Denise Peirce and Christopher Rice, filed an application, pursuant to RSA 193:3, with the Claremont School Board, seeking permission to provide home education for Denise’s son, Justin. The plaintiffs subsequently revised the application on two occasions. After a hearing on July 29, *7641980, however, the Claremont School Board (the local board) voted to deny the plaintiffs’ request.
In June 1980, the State Board of Education adopted “Regulations and Procedures Pertaining to Home Education Programs in New Hampshire.” The regulations, which were promulgated on a trial basis, became effective on July 2,1980, and recently expired on July 2, 1982. They established several prerequisites to the granting of a home-education program, including a requirement that the applicant prove the existence of a “manifest educational hardship.” See Regulations pt. I, § 2 (1980). In addition, the regulations contained a section, entitled “Due Process Procedures,” which stated that upon the denial of a home-education application, the local school authority had to provide a written description of any deficiencies in the application as well as written recommendations for correcting these deficiencies. See id. pt. Ill, § 2.
Because the plaintiffs had filed their application prior to the adoption of the State regulations, the Claremont School Board did not fully comply with the regulations while processing the May 1, 1980, application. As a result, the local board permitted the plaintiffs, on October 3, 1980, to submit a supplemental application which was to be evaluated in light of the newly adopted regulations. Following a hearing on the supplemental application, the local board found that the plaintiffs had not proven the existence of a “manifest educational hardship” as defined under the State regulations. The local board therefore denied the plaintiffs’ supplemental application.
In December 1980, the plaintiffs filed a timely appeal with the State Board of Education under RSA 193:3. Shortly thereafter, the State board conducted a hearing and determined that the plaintiffs had failed to demonstrate a “manifest educational hardship.” The State board also ruled that the local board had sufficiently complied with the due process procedures of the State regulations. The State board affirmed the decision of the Claremont School Board and denied the plaintiffs’ request for reconsideration. The plaintiffs then initiated this appeal. See RSA 541:6.
The plaintiffs argue that the State board erred when it found that they had not demonstrated a “manifest educational hardship” within the meaning of the home-education regulations.
Because the plaintiffs’ argument revolves around the alleged existence of a “manifest educational hardship,” we must examine the meaning of this term under the applicable regulations. Part II, section 2.2 of the regulations stated that a “manifest educational hardship” would be considered to exist upon an objective showing that the applicant’s child would derive “special benefits” from a *765“quality home education program.” Part II, section 2.2 also set forth nine factors which were designated as “quality indicators.” These indicators included criteria such as the competency of the parents, the scope of the subject matter to be studied at home, the child’s potential for interaction with peers and adults, and the teaching methods to be employed.
The introduction to part II, section 2 of the regulations stated that a “manifest educational hardship may be considered to exist when one or more [quality] indicators are present.” (Emphasis added.) The plaintiffs argue that this section required the State board to find a “manifest educational hardship” upon proof of any one of the nine indicators.
We disagree with the plaintiffs’ interpretation. We hold that the use of the word “may” in the introduction to part II, section 2 was intended to make the finding of a “manifest educational hardship” permissive, rather than mandatory. See Town of Nottingham v. Harvey, 120 N.H. 889, 895, 424 A.2d 1125, 1129 (1980). See generally 2A C. Sands, Sutherland Statutory Construction § 57.03, at 415-16 (4th ed. 1973). The language in part II, section 2.2, moveover, supports our construction. This section stated that the quality indicators were merely factors which “[might] be considered” in determining whether a child would derive special benefits from a home-education program. As a result, we conclude, contrary to the plaintiffs’ argument, that the regulations provided the State board with a certain degree of discretion in determining whether special benefits or a “manifest educational hardship” existed. Furthermore, we interpret the phrase “special benefits” (emphasis added) according to its common usage, see RSA 21:2, to mean benefits which are distinct or noteworthy.
Having examined the general requirements for a “manifest educational hardship” under part II, section 2.2 of the regulations, we turn briefly to the applicable standard of review on this appeal. We must uphold an agency’s decision, in the absence of an erroneous ruling of law, unless we find by a preponderance of the evidence that the decision was unjust or unreasonable. RSA 541:13; see Appeal of Society for the Protection of Environ. of S.E. N.H., 122 N.H. 703, 706-07, 449 A.2d 1205, 1207 (1982); Appeal of Town of Goffstown, 121 N.H. 999, 1001, 437 A.2d 291, 293 (1981); Appeal of Gas Service, Inc., 121 N.H. 797, 799, 435 A.2d 126, 128 (1981). In reviewing an administrative decision, we will treat the agency’s findings of fact as prima facie lawful and reasonable. RSA 541:13; see Appeal of Gas Service, Inc., 121 N.H. at 799, 435 A.2d at 128. We will not substitute our judgment for that of the agency. Appeal of *766Concord Natural Gas Corp., 121 N.H. 685, 692, 433 A.2d 1291, 1296 (1981).
In this case, we find that the evidence raised legitimate questions which might reasonably have led the State board, in its discretion under the regulations, to rule that the plaintiffs’ proposed home-education program would not have provided Justin with special benefits, the prerequisite to a “manifest educational hardship” under part II, section 2.2. The record reveals that neither Denise Peirce nor Christopher Rice had a college degree or any other special expertise. The record also indicates that the proposed home-education curriculum involved limited and irregular hours of organized instruction. For example, Christopher Rice testified that he intended to instruct Justin for two hours in the morning and for an unidentified period at night but that these hours would be readjusted if Justin preferred to play during the scheduled times. Rice further stated that Justin would be free to play between the hours of noon and 6 p.m., and that on some occasions Justin would be permitted to play all day long. Based on this evidence, we cannot say that the State board’s finding, that the plaintiffs had failed to demonstrate special benefits or a “manifest educational hardship,” was unreasonable or unjust.
The plaintiffs also argue that the State board erred when it ruled that the Claremont School Board had sufficiently complied with the “Due Process Procedures” of the regulations. As previously mentioned, the regulations, pt. Ill, § 2, required local school authorities to provide all unsuccessful home-education applicants with written recommendations for rectifying any deficiencies in their applications. The record before us, however, reveals that the Claremont School Board never provided the plaintiffs with written recommendations for correcting the deficiencies in their application. It is well settled that administrative boards must enforce their own rules and regulations. Appeal of the City of Nashua, 121 N.H. 874, 876, 435 A.2d 1126, 1127-28 (1981). The State board therefore should have required the local board to provide the plaintiffs with the requisite recommendations. For this reason, we reverse the State board’s ruling concerning the local board’s compliance with the “Due Process Procedures” of the regulations, and we remand for enforcement of the recommendation procedures.
Following the issuance of written recommendations by the Claremont School Board, the plaintiffs should be given an opportunity to correct the deficiencies and to resubmit their application for approval by the local board. If the local board denies the revised application, the plaintiffs may again appeal to the State *767board. The appeal to the State board would be governed by the regulations discussed in this opinion notwithstanding the expiration of these regulations on July 2,1982.
In closing, we emphasize that the local board must provide the plaintiffs with clear and constructive written recommendations. Nevertheless, without intending any reference to the instant dispute, we recognize that in some cases the deficiencies in an application may be of such magnitude that there is little or no chance of correcting them. In these cases, the local boards would satisfy their obligations under the regulations by identifying the specific deficiencies and explaining why they consider the deficiencies irreparable.
Affirmed, in part; reversed in part; remanded.
Douglas and Brock, JJ., concurred specially; the others concurred.