Greensboro, N.C. — The historic action by four students that led to desegregation at lunch counters more than half a century ago shows how young people can change their world for the better, first lady Michelle Obama told a crowd of 15,000 at North Carolina Agricultural and Technical State University's graduation Saturday.

"Congratulations. You all have worked so hard, and I know you have grown so much, and you have come to truly represent represent something called Aggie pride," Obama told the more than 1,200 new graduates of the historically black university in Greensboro.

In 1960, four N.C. A&T students put their careers and lives on the line by sitting down at a segregated Woolworth's lunch counter a few miles from campus. They asked to be served coffee and were refused, but they returned day after day in greater numbers. Others across the South followed their example until the company eventually ended separate treatment of black and white customers.

"It all started because a small group of young people had eyes open to the injustices around them," Obama said. "They were fighting so all of you and me could have opportunities that they couldn't even imagine."

The first lady urged the newest N.C. A&T graduates to become similarly active in civic life.

"Being engaged means not simply recognizing what's wrong, not simply complaining about and talking about our problems, but acting," she said.

Many graduates said they were inspired by the first lady's address and feel ready to take on the real world.

"I got a little bit more weight on my shoulders as far as representing my community," said graduate Derrick Smith.

"I just plan to actually sit down and do some evaluating and ask myself those questions and see how I want to have a hand in the community," graduate Deonne McNeill said.

Obama's N.C. A&T speech came in a year when North Carolina is considered a battleground state in the presidential election. Her visit was expected to generate goodwill within a core Democratic Party constituency as her husband seeks re-election this fall.

She steered clear of references to politics and her husband's re-election bid, although the audience cheered when she told graduates, "We have the responsibility to protect the ground that has already been won, because it can just as easily be lost."

Obama also received an honorary degree from N.C. A&T.

She also served as commencement speaker at Virginia Tech Friday and will speak June 17 at Oregon State, where her brother, Craig Robinson, is the men's basketball coach.