All 40 science projects will be on exhibit this weekend.The exhibit will be open to the public from 1 to 4 p.m. Saturday and Sunday at the National Academy of Sciences, 2101 Constitution Ave. NW.

Michael Reidy had always been fascinated with biochemistry, so for his 10th grade science project he decided to make a population study of bacteria.

Reidy was such an eager student that he got an early start on cultivating the tomato's juice base in which his microorganisms would grow. And since he was running ahead of schedule, he just stuck the juice, yeast bacteria, and all, into the refrigerator.

Not long afterward, Reidy and his family ate his experiment, with spaghetti, for dinner.

"It was quite nutritious, actually," Reidy says now. "We didn't realize it until a couple of days later. Our reaction was hysteria and laughter -- after a moment of panic."

Reidy is 18, but he recalls his past scientific frivolities with an aura of professional assurance. This demeanor comes naturally since he's in the big leagues now. Reidy, who lives in Springfield, is the only finalist from Northern Virginia in this year's Westinghouse Science Talent Search, which culminates with a five-day science fair beginning today at the National Academy of Sciences in Washington.

The biochemical research project that brought him a finalist's spot has a long name that incorporates Greek, Latin and a tongue-twisting acronym. In laymen's lingo, the project has to do with predicting the behavior of enzymes in yeast molecules.

In dollar signs, just being selected as one of 40 finalists gets him $500 (and, Reidy notes with a smirk, "an all-expense paid trip to Washington, D.C."). If he places in the top 10, he could receive a scholarship ranging from $5,000 to $12,000.

But Reidy claims to have little interest in the money, even though he has applied almost exclusively to high-prestige, high-priced Ivy League colleges. The real reward, he says, are the contacts he makes during the five-day fair and being able to list the award on college applications.

"I'll have a long string of interviews with some of the most prominent scientists," said Reidy. "I'll meet three Nobel prizewinners and the president of the Nobel Foundation in Stockholm. The scholarships are more the icing on the cake."

Reidy, a senior at West Springfield High School, says his interest in science developed from "a general curiosity."

Reidy's public school education in science has been supplemented by a summer at the National Science Foundation at Indiana University, where he refined the idea that resulted in his Westinghouse project. He remebers with satisfaction the last-minute frenzy in Bloomington, when he puts the finishing touches on his experiment.

"In the final (five) days, I had three hours of sleep, nine hours for meals and showers," he said. "But I felt great."

His project was chosen by the Westinghouse judges, Reidy believes, because it showed an advance ability for a student of his age and because he was able to carry his conclusions one step further, to make a prediction beyond what his results actually showed.

"It won because of the complexity of the project for a high school student," said Reidy. "And out of that, I did a series of things and cross-referenced them. Through watching trends, I was able to . . . predict the bonds in the molecule."

As for the implications of his findings for mankind, Reidy has no great illusions.

"The numbers I turned out will go in some book," he said. "My research is not all that conclusive. But the general research is important for medical reasons . . . for bone repair and the reduction of antibodies. It can apply to cancer or the common cold. Understanding cell biochemistry can take you down innumerable paths."