"I need to talk to you, ladies and gentlemen, about reading," Jerry Wilkening tells a cluster of sixth graders in his class at Mount Vernon Community Center School in Alexandria.

"Before you answer my question, I want you to think a minute. Can you think of any reason why you wouldn't be able to find the distance from Earth to Mars in a world atlas?"

There is silence, some crackling of homework papers. Then one girl ventures: "Because Mars is not in our world."

Wilkening nods. Her answer is right. In the previous night's homework, nearly everyone got it wrong.

Wilkening hardly ever asks a question that can be answered "yes" or "no." Instead, he asks such questions as "Why did the author write this story? . . . Can you think of two possible answers to that question? . . . What does he mean when he says, 'They could run as fast as the wind.?' "

This is the way Wilkening likes to teach. And this year, he is being encouraged to pepper his classes with even more open-ended questions as part of a pilot project to strengthen critical and creative thinking in the school of 750 students. Mount Vernon is one of five schools in the nation in a three-year program, sponsored by the National Education Association, that is trying to boost learning from within schools rather than through state-imposed reforms.

"The whole idea is to get these kids to sit down and think," Wilkening said recently. " The project has made me more aware of the fact that these kinds of questions can be utilized more than we do."

At the heart of the project, called "Mastery in Learning," is the conviction that public school teaching can push beyond the surface comprehension of multiplication tables and historical dates, said Robert McClure, the NEA director for the project.

"We were concerned," he said, "that youngsters be able to write intelligently and persuasively as well as correctly; that they be able to compute but also understand something about the elegance of mathematics."

The project, which will be expanded to 24 schools in the fall, tries to prod students toward "higher-level thinking -- to being creative, recognizing the difference between propaganda and truth, being more critical about the world . . . to put it in the most grand way, to be a good citizen," McClure said.

The idea of teaching critical thinking has gained momentum around the country and in most Washington area public school systems in response to the back-to-basics movement; many educators became concerned that students were being force-fed facts at the expense of understanding.

Critical thinking "is a national movement under way now," said Ron Brandt, executive editor of the monthly journal of the Association for Supervision and Curriculum Development. "Educators are deeply interested in this. They feel there's been so much pressure for achievement that teachers have felt obligated to get the kids to learn what's on the tests."

While many educators support the idea of teaching thinking, they agree its practice is tangled with difficult questions: Should teachers weave critical thinking into the regular curriculum, or should they teach it as a separate subject? How can you tell when students have progressed?

At Mount Vernon, there is no "critical thinking" hour in the schedule; there are no textbooks with take-home thinking drills and few tests that assess the skill directly. There is, instead, the measured, daily exchange between teacher and students.

The subject is the European colonization of Africa and the roots of the slave trade.

"What type of person do you suppose it would take to be a slave dealer?" Wilkening asks.

"A cold person," one student says.

"A person with no feeling for others."

"A self-centered person."

"I don't understand," says 11-year-old Justin Kincaid, "how someone could be so mean to people just because of their skin color, when they're just the same as anybody else."

"Well, do you suppose the slave dealers looked upon the slaves as people?" asks Wilkening. "What did they think of them as?"

"Animals," call several students in chorus.

"But you'd still have it on your conscience, about how you treated people unfairly," says Justin. "I wouldn't be able to live with that."

McClure believes the initial wave of education reform, set in motion by the U.S. Department of Education's 1983 "Nation at Risk" report, overemphasized standardized tests as a gauge of students' progress.

"The mandates from outside of school have practically forced schools to stress easy-to-measure student outcome," he said. "You've got to go for the easy stuff -- the easy stuff has begun to permeate what's happening in the schools."

Advocates of teaching critical thinking say they are not dispensing with required curriculums or basic facts -- they are helping students retain, use and analyze those facts.

"Critical and creative thinking is not at odds at all with back-to-basics, and it's not that difficult to teach," Wilkening said. "If you're studying ancient Rome, the kids have more fun with a question like, 'If you could interview Julius Caesar, what would you ask him?' You can't think what to ask him unless you know something about the man."

In Arlington, social studies teachers began several years ago to target and test critical thinking skills, using workbooks and examinations that they wrote themselves. Students in the fifth, seventh and 11th grades take the test each fall and spring, and the scores always go up, said social studies supervisor Seymour Stiss.

Last year, the average score of fifth graders on the thinking test rose from 76.8 percent correct in the fall to 84.4 percent in the spring; seventh graders improved from 75.9 percent to 84.1 percent and 11th graders from 85.1 percent to 89.9 percent.

Educators say that although such tests can measure specific kinds of reasoning -- the ability to deduce, draw analogies or tell the difference between fact and opinion -- teachers cannot rely on easy, standardized methods to gauge overall thinking.

"Writing is a good way to find out where students are in regard to critical thinking skills," McClure said. "But we need a whole variety of pencil and paper instruments and human ways of assessing progress . . . having teachers ask the tough, leading questions."

The class talks about European hunters in Africa, about the many animal species that are extinct or are threatened with extinction. Xavier Gardin, 11, suggests that people create tropical parks in Florida or another warm climate and let wild animals live in them and reproduce.

"Why do you suppose more land isn't set aside for that kind of thing?" Wilkening asks.

"Climate," suggests one boy.

"They don't have the money because the government is spending it on other things," another says. "Like the homeless, and building houses."

"Well then, the government should take 5 percent off our parents' taxes and put it toward tropical game parks ," says another pupil.

"No, because then your parents wouldn't get back as much money, and you've got to eat, too," answers a classmate.

Wilkening is smiling. "You know, you all sound like a bunch of senators and congressmen. These are the basic issues. This is what adults argue about all the time."

Some advocates of a rigorous back-to-basics curriculum question the value of teaching critical thinking. At a recent public meeting in Arlington to discuss social studies instruction, several parents argued that teaching students how to think could easily lapse into telling them what to think.

"It's essential that kids have facts, that they don't go into class and get role-playing and 'what-do-you-think' all the time," Knute Hansston, a parent, said at that meeting. "Are we sometimes guilty of trying to train our kids to think in a certain way?"

"We're not interested in telling kids what to think; we're helping them learn how to think," said Stiss, the social studies supervisor. "I can't enfold in your brain a bunch of facts, but I can teach you to find the facts when you need them."

Sometimes, teachers said, students themselves resist learning to question and analyze.

"Kids are not happy with it," said social studies teacher Bonnie Pfoutz of Wakefield High School in Arlington. "They want yes or no answers."

"Sure, students will say, 'What are you asking me for? Why don't you tell me what you want me to know and go on from there?' " Stiss said. "But you have to resist that. We want people to know how to use facts."

In the long run, said Wilkening and other advocates of teaching how to think critically, students will retain information they have thought about rather than merely memorized.

"I believe the standardized test scores will go up," McClure said. "I think youngsters in the kind of program we are trying to develop will care more about school . . . youngsters will be able to think more creatively and imaginatively. They will be more excited about learning. Those feelings are harder to measure. But they are the most important qualities."

Wilkening writes "Liberia" and "Ethiopia" on the blackboard. A student volunteers that Liberia's official language is English.

"Why would they speak English? What's the connection?" Wilkening asks. "And the capital, Monrovia. Why would it be called that?"

No one answers; some students start thumbing the index of their social studies texts.

"You think about it," Wilkening says. "The book is not the answer for everything."