Cambridge, Mass. — Pushing a pencil behind his ear, high school senior Ben Gagnon announces the Soviet delegation's decision to blockade Yugoslavia - a communist country in Eastern Europe which has long repelled Moscow's domination.
Thus begins the first round in a classroom simulation designed to teach the fine points of conflict resolution to teen-agers. The goal: Avoid letting international tension escalate into nuclear war.
While most observers would agree this objective is noble, that's where agreement ends.
Supporters of classroom simulations and curriculum materials dealing with nuclear war and arms control say it's important to address the deep concerns students have about war. But critics, which include some parents and educators, charge that much of the material is being foisted onto schools by groups with ideological axes to grind.
The Yugoslav scenario was developed by Ground Zero, a Washington-based educational organization which - while not officially backing specific legislative measures such as a nuclear freeze - does promote arms control and improved relations with the Soviet Union.
''This is your basic pitch for negotiation,'' teacher Roz Grumman says as she pins up a chart showing the relative clout of the US and Soviet nuclear arsenals. The game has no specific rules, she continues, ''except to deal with each situation as it comes up.''
So for the next 45 minutes, students in Room 502 at Cambridge Rindge and Latin, a public high school, become superpower policymakers during an imaginary day in April 1988 - when pro-Western forces have snatched control in parts of Yugoslavia, while Cuban troops are poised to move into Nicaragua.
This simulation is part of a course entitled, ''Decisionmaking in a Nuclear Age.'' It illustrates the nationwide movement toward teaching about nuclear war.
At least a half-dozen groups - such as Educators for Social Responsibility and Jobs with Peace - are publishing curriculum materials dealing with the subject. Most of the materials targeted high school students, but some start in elementary grades.
''If our children learn peacemaking skills when they're young, they'll carry these into adulthood with them,'' says Fran Schmidt, a sixth-grade teacher in Miami who mixes nuclear issues into classwork. Her 34 students, for instance, have written letters to President Reagan and Soviet leader Yuri Andropov telling of their concern about nuclear war, and conducted a public opinion poll on a local nuclear freeze referendum.
Research conducted under the auspices of the American Psychiatric Association shows that about 40 percent of children learn about nuclear weapons before age 12. The studies also suggest many of these children are deeply concerned about the prospect of war - a point usually highlighted by backers of the new curricula.
The advocates say their goal is not to emphasize the consequences of war, but to teach children about ways in which international conflict might be avoided.
''Children need to learn how to actively enter into democratic decisionmaking processes,'' so that they don't feel helpless about the future, says Roberta Snow, an educator who recently joined the Harvard Medical School faculty to study the effects that classes dealing with nuclear war have on children.
Ms. Snow, together with several other teachers, wrote a curriculum on nuclear issues designed for high school students. When it comes to younger age groups - junior high and elementary school - Snow says teachers need to be very careful.
''There are damaging ways to teach this stuff,'' she says. ''Some teachers go in and show scary movies to 'wake' the kids up.'' Because of this possibility, Ms. Snow urges parents to get involved in overseeing how any nuclear curriculum is taught.
Younger children, experts agree, should not be shown graphic pictures of nuclear destruction. But with older students, there's less agreement. Some social reformers cling to the notion that startling pictures can help prompt action, much as it did when television brought the Vietnam War into American living rooms in the late 1960s.
''Parents are very concerned about kids getting fed a lot of political propaganda in the classroom,'' says Shelley Berman, director of the Boston chapter of Educators for Social Responsibility (ESR), which distributes a 200 -page curriculum guide for elementary and secondary school teachers.
Mr. Berman contends the ESR guide looks at all sides of the issue and urges teachers not to unduly frighten youngsters. But some communities have rejected the group's curriculum.
''The stuff they showed us was strictly antinuclear; there was no balancing point of view,'' says John McDonough, a parent in Maynard, Mass., where a proposal to use ESR's curriculum guide was rejected last fall. If the school allowed this sort of material in, says Mr. McDonough, ''every other special interest group might also want in - including the John Birch Society and the Moral Majority.''
The groups promoting nuclear war curricula admit they have strong political stances on the issue, but insist their materials can be objective.
In most communities where the subject is being addressed, the curriculum is meshed into existing courses such as history or social studies, making it difficult to pinpoint exactly where the subject is being taught.
''We feel the integrated approach is the most effective,'' says ESR's Mr. Berman. ''If you have a special course, it's too easy to cancel when the money gets tight.''
A home economics class at Lincoln-Sudbury Regional High School in suburban Boston, for instance, includes a one-week unit called ''World Hunger and the Arms Race.''
Laurie Baumgarten, a fifth-grade teacher in Berkeley, Calif., says she uses history lessons to address childrens' concerns about nuclear war. For example, she recently taught students analogies between the abolition, women's rights, and disarmament movements: ''They all show how people can work to change things they don't like in society.''
For now, the most controversial curriculum is ''Choices: A Unit on Conflict and Nuclear War,'' developed by the Union of Concerned Scientists (UCS), an antinuclear group, and the National Education Association (NEA) and published earlier this month.
''There's no question in my mind but that the NEA materials push kids in a particular direction - that's in favor of a nuclear freeze,'' says Cliff Kincaid , associate editor of Human Events, a conservative weekly published in Washington. Mr. Kincaid is trying to stir action among conservative groups and members of the Reagan administration to try to ''add some balance to the materials.''
Officials at the NEA and UCS insist that the original materials, which were tested in 47 classrooms last fall, have since been purged of political bias. For example, ''some people felt we hadn't covered the option of peace through strength sufficiently, so we increased that element,'' says Natalie Goldring, a UCS spokeswoman.
Many teachers, meanwhile, say nuclear issues are likely to continue surfacing in the classroom, regardless of what happens to the new curricula.
''Students want to know what the government is doing. They want to know where the money is going and how they can get involved with those decisions,'' says Venessa Kirsch, a senior at Cambridge Rindge and Latin who is now considering writing a curriculum herself.