Remember the first time you saw the Periodic Table of Elements? Its inscrutable rows of little boxes were supposed to reflect the properties of the elements -- to help you "think like a scientist."

But all you could think was: "I'll never learn the difference between magnesium and manganese!" Or "Why can't the symbol for lead be Ld?"

While many middle-class students come to see the wisdom of the Periodic Table with effective teaching, kids in underresourced schools often lack the necessary support, and they opt out. For Wendy M. Williams, professor of human development, how the Periodic Table is traditionally taught has become a symbol for why disadvantaged youth have so much trouble turning on to science.

"The scientific method is a perfectly good way to do fact-finding, reasoning and analysis about real-world problems of everyday life, and it is essential that we bring this message to underserved youth," says Williams, who gave a featured research presentation on her "Thinking Like a Scientist" program in May at the Children, Youth and Families at Risk Conference in Chicago. With good teaching, kids come to appreciate the Periodic Table as a thing of beauty and a useful tool, she says. "But if we tell them they have to learn the Periodic Table before they can think like a scientist, then most would rather not."

And they will lose, perhaps forever, the chance to acquire skills they need, to discover for themselves the truth and what it means, and to be liberated from the "thought police" -- television advertisers, closed-minded parents or prejudiced schoolmates. They also lose a valuable mechanism for escaping the cycle of poverty through education and careers in science.

So Williams, with former graduate students Matthew C. Makel, Paul Papierno and David M. Biek, has been developing the Thinking Like a Scientist (TLAS) curriculum with National Science Foundation support. Its lessons have been tested at inner-city schools in Chicago and with underprivileged white, Mexican-American, African-American and Native American students in Arizona, North Dakota, Iowa, Alabama and upstate New York, where many drop out during high school and few consider careers in science as even a remote possibility.

Williams has found that in every classroom in which it has been tried, score improvements have been larger for students in TLAS classes than in the neighboring classes (control groups), and that those who have taken the TLAS curriculum come to excel in tests that measure scientific thinking ability.

The curriculum teaches students how to find out facts for themselves and how to use proven information to make important decisions in their daily lives.

For example, TLAS students learn to uncover information from recently published meta-analyses in major scientific journals. The lessons focus on everyday topics -- whether violent video games make youth more violent in real life, whether and how to treat adolescent depression, and whether cigarette smoking really relaxes people (as they claim). Students learn the many ways the scientific method can help answer such questions. By defining the problem, seeing multiple sides of an issue and distinguishing fact from opinion, they learn how to determine what constitutes evidence and how to weigh evidence and make scientifically informed decisions.

The ultimate target for TLAS, says Williams, co-director of the Cornell Institute for Research on Children, which sponsors the education-outreach project, are youth of color and youth from economically disadvantaged backgrounds, we well as girls who traditionally do not pursue science education and careers.

Williams, herself, came from a disadvantaged background -- she was a high school dropout at age 16 who later earned a G.E.D. and wound up graduating from Columbia and earning two master's degrees and a Ph.D. from Yale. She is implementing the curriculum this fall in cooperation with Cornell Cooperative Extension in New York City in high schools serving African-American and Latino youth. The project is partially supported with a three-year Smith-Lever federal funds grant.

This article is abridged from Cornell Human Ecology Magazine. Roger Segelken is a writer and consultant with the Office of Publications and Marketing.