Before machinery, a single farmer could raise only 7 1/2 acres of wheat a season.

The idea of using barbed wire came from the Egyptians.

Coca-Cola was once considered an aphrodisiac.

Since Thursday, several hundred exhibits containing thousands of miscelleanous facts and created by junior high and high school students from 30 states have been on display in the University of Maryland's Student Union. This afternoon, on National History Day, a year-long program of state and district competitions will culminate when awards for the most imaginative and historically accurate projects will be presented at Tawes Theatre.

Yesterday a group of social studies teachers and history professors judged the harvest of scholarship and creativity: written reports, maps, diagrams, slide shows, tape recordings, crafts and family heirlooms. Many exhibits were proudly narrated by students dressed as cowboys, oil drillers, coal miners, court jesters and prairie damsels with bonnets.

The purpose of National History Day is to instill in young people an appreciation of who they are and where they came from. As Lois Scharf, a part-time history professor at Ohio's Case Western Reserve University and executive director of National History Day, put it, "In the '60s came the battle cry for relevance with emphasis on contemporary crises and absolutely no historical perspective." Since then, she continued, disciplines such as economics, psychology and sociology have gradually replaced the conventional social studies -- namely history -- in the public school system.

This year's theme was "Work and Leisure," and although entries could cover any country and any time period, many of the projects dealt with the history of the students' own communities. Betsy Harter, Catherine Mehl and Melinda Metzer, all eighth-graders from Billings, Mo., studied "Inventions That Changed the Farmer's Work" and focues on the Oliver Plow, the McCormick Reaper and Glidden's barbed wire. Wearing lacy dresses, their hair neatly combed and sprayed in place, they solicited the attention of passing judges by waving sheaves of wheat at them and smiling sweetly.

Did you know that the Harmony Society of Pennsylvania, which established utopian communities in the early 1800s and practiced celibacy, manufactured and sold whiskey, beer and wine? They drank mainly the wine because they considered beer and whiskey too strong. But they drank the whiskey for medicinal purposes.

"They prepared for the coming of the Lord," said Betsy Johnson, a wide-eyed seventh-grader from Beaver County, Pa., as she pointed to her Harmony Society display. "So they didn't have any children, so they died out."

Some students presented their views of history dramatically. Dawn Daly, Ken Fox and Pam Butler, high school students from Hazelcrest, Ill., performed scenes from "A Raisin in the Sun" and read from their biography of Lorraine Hansberry, the black playwright from Chicago who won the New York Drama Award in 1959 for "Raisin." She died of cancer in 1965. Butler cried as she read passages from letters Hansberry wrote while in the hospital.

Lance Wikoff, a 12-year-old from Stillwater, Okla., became interested in oil drilling because "I just liked to be with my grandpa and he spent all his time at the drills. My grandpa and his dad worked in oil, and my other grandpa and dad worked in oil, and I've made up my mind to go into it, too." Wikoff was dressed in a blue work shirt and overalls and was disappointed that he couldn't bring any pipes along with him for his project, "Oil: Drilling Through the Years." But "as soon as I get through with this," he said, "I get to go sightseeing."

At the awards ceremonies today will be announced next year's grant of $186,000 to the National History Day program from the National Endowment for the Humanities, according to Scharf. "We're pleased with it," she said, "but it reflects a substantial cutback." The last grant, for a two-year period to expand the program, was $750,000.