AMES, Iowa (AP) _ For those competing in Odyssey of the Mind, the answer could be turning a bicycle wheel into a musical instrument or thinking like a cat. Just as long as they're creative.

''We're too quick to make heroes out of people who can knock other people down. These kids are using their imaginations. It's without a doubt the most upbeat experience,'' said Sam Micklus, the program's founder.

More than 5,000 students from 19 countries are competing in the world finals of the problem-solving competition at Iowa State University. Opening ceremonies were Wednesday and trophies will be handed out Saturday.

Events include:

- Building a balsa wood structure that can hold the most weight and then release a ping-pong ball when it collapses.

- Performing a humorous skit about the life of an animal from the animal's point of view.

- Building at least three mini-terrain vehicles that can dodge obstacles and then break a balloon target.

For the last nine months, teams have been perfecting their performances, often working night and day as the finals approach.

''It got to the point where we would all end up eating at someone's house,'' said 16-year-old Christy Champagne of Amherst, N.H.

She and her teammates are in the ''Believable Music'' category where they have to build at least three musical instruments and play a tune on them.

The finals bring together 712 teams. That's a far cry from the first competition in 1978, when 28 schools from New Jersey participated.

More than a million students from kindergarten through college participated in Odyssey of the Mind in 1994.

''It's a chance for an awful lot of kids to get a pat on the back for using their heads,'' Micklus said.