Detroit has gotten tough with its teen-agers. First, it tagged youths under 18 with a 10 p.m. summertime curfew (11 p.m., Fridays and Saturdays). Then, a month ago, it clamped down on school security after a series of violent incidents.
Security teams began making unannounced sweeps of the city's 22 comprehensive high schools in October. Students and their lockers have been searched with hand-held metal detectors.
So far, five students have been expelled for carrying weapons, and eight more face the same penalty for having weapons in school. High school students are required to have identification cards showing at all times. Students without a card are not allowed into the building. Under other circumstances, the security measures might have caused a public uproar. But the severity of the incidents - three students have been killed this school year alone - prompted a somewhat unexpected response.
''People applauded it,'' says Richard Levey, assistant to Detroit's school superintendent. School administrators, who had prepared for a deluge of phone calls from angry parents on the first day that the measures were instituted, say they heard scarcely a peep.
''Everyone saw the seriousness of it,'' says Robert D. Dickerson, assistant principal at Murray Wright High School. ''The students know what's expected of them, and they're doing it.''
''Most students felt it was necessary,'' agrees Steven Hayes, a junior at the high school.
Teacher authority had eroded so greatly that such severe measures were needed to reestablish a learning environment, says Edward Simpkins, a parent with a daughter in a Detroit public school and dean of the education school at Wayne State University located here.
The incidents have tended to be isolated and have sometimes been caused by outsiders rather than students, he explains. ''It's not just a replay of the gang activities that took place in other schools.''
Some groups have had reservations about the security measures.
A committee of lawyers for the local branch of the American Civil Liberties Union is studying those measures to see if they violate the constitutional rights of students. Their report is expected soon.
Although the security measures and school violence have overshadowed the academic improvements in city schools, which are now 93 percent minority, Mr. Levey says, they do seem to have generated community support.
Administrators discovered that a number of schools had not involved parents and students to a great degree, and they are working to improve that situation. Police have begun working more closely with the Board of Education. Last week, a number of police reservist volunteers were deployed in 10 city high schools, helping out the school guard staff, which was severely depleted by layoffs in 1981.
And William Sledge, president of the Woodbridge Citizen District Council, a federally funded citizen group, says his organization may soon begin a cooperative effort of its own to help beef up school security. ''We want to see protection for our neighborhood,'' he says.