If you've ever seen Supreme Court Justice Clarence Thomas speak to a group of students, you know how energized and enthusiastic he becomes. That was the case Tuesday night when Thomas served as the keynote speaker for an event celebrating the 27 winners of a nationwide high school essay contest. The contest is sponsored by the Arlington, Va.-based Bill of Rights Institute, a 10-year-old organization that develops programs and curricula for high schools on the nation's founding documents. The contest has become the largest in the country, says institute founder Victoria Hughes. This year it drew 31,000 entries.