WATERLOO - A throng of students gathered around a half-dozen third-graders as the music thumped at the St. Edward Catholic School gym Friday.

In the center of the crowd, the third-graders swiveled to keep Hula-Hoops going.

One-by-one, the twirling students dropped out until there were only two left spinning the hoops. The faces of the finalists were fixed in concentration as the crowd chanted their names.

Finally, a hoop spiraled toward the floor, leaving Elizabeth Weidner the winner. She walked up to the DJ table to collect her prize: a string of red raffle tickets.

The Hula-Hoop contests were just one event in two hours worth of dancing, games and fun to raise money for children with cancer.

The "mini dance marathon" was a first for the school, and more than 200 students packed the gym to take part, said Principal Pam Schowalter.

"We didn't know what to expect for our first time," said Karen Nank, the student council coordinator. "It's a good thing our gym isn't any smaller."

Parent Christie Wood of Waterloo said her two daughters - one in preschool and the other in first grade - had a blast.

"They're having a great time, and they're doing it for a good cause," Wood said.

Proceeds from the mini marathon will go to the pediatric oncology and bone marrow unit at the University of Iowa Hospitals and Clinics in Iowa City, said Eric Banwarth, a UI student from Dubuque who worked the gym as a morale captain.

The money will pay for travel, lodging and prescription co-payments for prescriptions for children treated at the unit, Banwarth said. He said some will also go toward research.

Area merchants donated raffle prizes for the St. Edward event, and the goodies included Nintendo DS video games, iPod music players and Columbus School apparel, Schowalter said.

University of Iowa students will have their own 24-hour dance marathon to benefit the program Feb. 6.

For more information about the University of Iowa Dance Marathon, go to http://www.uiowa.edu/~dancemar/index.html.

Contact Jeff Reinitz at (319) 291-1578 or jeff.reinitz@wcfcourier.com.