A sharp rap on the door interrupts the interview under way in Principal Ed Carangelo's office. The principal is needed because a student previously suspected of drug abuse is weaving precariously in the hall.
Mr. Carangelo's response is quick: ''Bring him to the guidance office. We don't want him getting hurt. I'll call his parents right now. I want them in the office today, so we can deal with his problem.''
This incident at Niskayuna High School near Schenectady, N.Y., is typical of the central questions raised in a recent report on student discipline by the US Department of Education: Are the people who run US schools free to make the decisions necessary for maintaining order? Or have American schools become so permissive, so uncontrolled, that they cannot fulfill their primary mission - preparing students academically for the adult world?
Violence and disruption are indeed major obstacles to better education, especially in urban schools, the report states. Each month 282,000 students and 5,200 teachers are assaulted in US classrooms. Twenty-five percent of American schools suffer some sort of vandalism every month.
In 14 of the past 15 years, discipline was identified as the most serious problem in education in a Gallup poll of public attitudes toward the public schools.
At a time when a host of national studies have focused attention on the shortcomings of the schools, discipline is one issue that ''seemed to be conveniently ommitted,'' says Scott Thomson, executive director of the 35,000 -member National Association of Secondary School Principals (NASSP).
''In many respects it's a national embarrassment,'' Mr. Thomson continues. But the blame doesn't rest solely on the the schools, he says. It must be shared by society.
President Reagan has proposed that the Department of Education find and publicize effective means of school discipline. He also wants the Justice Department to help local school districts defend themselves in lawsuits that might adversely affect their authority and to create a school safety center, which would provide information to schools about solving discipline problems.
But the problem is complex, and the solutions are not as simple as Mr. Reagan suggests, says Len Stafford of the National Education Association (NEA). Students who fail to get a solid academic foundation in the early grades fall farther and farther behind, Mr. Stafford explains, increasing the likelihood that they will be unsuccessful and disruptive in the later grades. Identifying these students in elementary school and providing them with remedial work and counseling might be one answer. Unfortunately, these are the very kinds of programs the Reagan administration has been cutting, says the NEA spokesman.
Not surprisingly, research on schools that have received recognition for excellence indicates they all share a climate of good discipline. Niskayuna High School, located in a white, upper-middle-class neighborhood outside Schenectady, received a presidential citation for excellence last fall. It boasts one of the highest average SAT scores in the nation.
The school's rules have been explained clearly to both students and parents. Use of alcohol or drugs on school grounds will result in an automatic five-day suspension. After an infraction, a student who returns to school also faces a five-week supervised suspension; when not in class, he or she must report to a special study hall. A third offense brings mandatory counseling with the school psychologist.
''What that principal (at Niskayuna) did is what the public needs to keep in mind about discipline - maintaining order while helping the student,'' says the NASSP's Thomson.
''Do we want our principals (to be) so tied up with legal paper work that they can't help a student? If you spend hours and hours on one case, you don't have time for the 1,500 other students and 200 . . . teachers in your building, '' says Thomson. The core issue, he says, is that Americans must develop a consensus which demonstrates that they expect ''students to exercise self-control at school.''
A 1979 NASSP survey of principals shows that 35.7 percent of those considering leaving the profession cite ''constraints caused by courts or legislation'' as the reason. The National Committee for Citizens in Education is ''sympathetic to what the teacher and principal must deal with,'' says Nancy Barla. But our educators ''need more classroom management in their teacher training. We would be concerned about any diminishment of due-process procedures in student rights linked to student discipline.'' Such diminishment leads to ''capricious and arbitrary'' use of suspension and expulsion, she adds.
The NEA's Mr. Stafford points out that the statistics used by President Reagan are six years old. (They were collected in a study by the National Institute of Education.) Though the problem hasn't gone away, it isn't as bad today as the 1978 figures indicate, Mr. Stafford says. Since that time many school districts have been developing strategies that go beyond simply getting tough.
The 72,000-student Charlotte-Mecklenburg school system in North Carolina revised its rules 2 1/2 years ago to combat drugs, violence, and vandalism. Anyone violating those rules is suspended for the remainder of the semester plus all of the next semester. ''We make it very clear we are not going to tolerate any abuse of these rules, says Chris Folk, associate superintendent for communications. If there is a real violation, ''after due process hearings, the student is out.''
An important feature of the system at Charlotte-Mecklenburg and at many large schools across the country is that, even while suspended, a student still attends classes in a special program at an alternative site. ''They don't lose the year, but they lose the regular school program,'' says Dr. Folk. The North Carolina district also has a separate program for first-time drug abusers as well. Last year, 225 students were expelled, and so far this year the expulsions are running at the same rate.
In Miami, the school system has a policy of automatic expulsion for possession of narcotics or weapons. In Philadelphia, 500 students have been arrested since August because of Operation Stop, a program to curb vandalism and graffiti by inviting the public to phone in anonymously with reports about such incidents.
Students in the Dallas public schools were asked this month to sign a ''Code of Conduct'' book, guaranteeing ''a certain degree of good behavior,'' says spokesman Nancy Barker. The book has four chapters.
Chapter 1 explains the expectations of school authorities regarding behavior. It establishes a partnership among the student, parents, and principal, all of whom are expected to work together to meet the expectations. Chapter 2 lists the levels of violations: (a) minor; (b) disruptive; (c) illegal and outside of school board policy. Each level has an appropriate punishment determined by the principal. Chapter 3 lists school board policies. Chapter 4 is a contract which both student and principal are expected to sign. Even if a student refuses to sign, he is expected to abide by the code of conduct. Dallas also is establishing discipline plans for grades K-12. The emphasis will be on rewarding students for good discipline.