AT FIRST GLANCE, the threatened suspension of English teacher Cyril Lang for teaching Aristotle and Machiavelli to 10th graders seemed a simple and terrible mistake. To parents who have had to deal with fourth-rate teachers, Mr. Lang may have sounded like a model of excellence in his profession. He was giving his students work in the classics, putting before them the kind of stimulating study many parents would like to see more teachers offer. And compared with some hopeless teachers -- not so rare these days -- who do not even spell properly, Mr. Lang surely seemed an exemplary, one-in-a-million teacher. He was, after all, challenging students with provocative materials, demanding too much of them, not too little.

Alas, there is another side to this story. Some high school teachers consider it a great honor and prize to be given the job of teaching the brightest students in the school. These college-bound students are serious, sincere and most often well disciplined. They are a joy to teach. However, there are only so many exceptional students. And a high school teacher usually must face some students who are not completely serious about or very good at academic subjects. To teach these average students is not always inspiring, but they must be taught. And they must be taught in some orderly fashion, with teachers generally covering the same material -- so the grades remain a fair indicator of a student's ability and not a gauge of the difficulty of one teacher's particular class. It is important to note here, in Mr. Lang's case, that high school students in Montgomery County do not pick their teachers, as is done in some schools, and that Mr. Lang's 10th grade English course was a requirement. So a student arbitrarily placed in Mr. Lang's classroom would be at a disadvantage in competing for top grades with students in the rest of the school because of the comparatively high degree of difficulty of the course work in his class.

In the incident that sparked the threat to suspend Mr. Lang, the assignment of works by Machiavelli and Aristotle adds a predictably jarring note to the argument: A teacher is reprimanded for teaching the classics. But what if, as Montgomery County Superintendent Edward Andrews has noted, Mr. Lang had chosen some unsuitable -- say, pornographic -- material for students to read? Do not citizens and parents of the county have a right to exercise some control over school curriculum, unless they purposely give teachers free rein to use whatever books they please? The trouble is that Mr. Lang ignored the school board's decision on what 10th graders should be taught and held accountable for, and he ignored the county's reasons for having a uniform set of textbooks. He ignored those community-approved decisions even after objections had been raised to his private selection of course materials and after he had been told he could offer the classics as material to be studied for extra credit.

We hate this case -- hate coming down on the side of anyone, even when that side is right, who is objecting to the teaching of classics purported to be out of the reach of the kids. But Mr. Lang was wrong to ignore the community's decision. Suspending him seems unnecessary, unless he makes it impossible for the authorities to do otherwise -- which he will do if he is seeking to make a point of his supposed lack of freedom to choose books for his class. If that is his goal, then the school system should stick with its tough position. But if he can return to school and abide by the rules, why punish him? We don't presume to know what the motives of the parties to this dispute really are. But to the extent that Mr. Lang is an example of a competent teacher pressing his students to conquer difficult ideas, he has our admiration.