About 150 youngsters from Indio, La Quinta and Palm Desert will take to the floor in the Desert Sands Unified School District’s first ballroom-dancing competition later this month. Advertisement On May 16, students will tango, fox-trot, salsa, East Coast swing, or cha-cha their ways through the competition, said Bob Horn, who is co-organizing the event. Each dance will have its own competition with participants engaging in two dance-offs. Judges will select three couples to remain on the floor to compete for first-, second- and third-place medallions, Horn said. All competitors will receive a participation ribbon. The schools with the entrants who win first place in the competitions will also receive a trophy that will be displayed for a year, Horn said. Horn and his wife, Nancy, who are professional dancers, held free dance lessons for after-school-program teachers at schools in the district. Those teachers then taught children in their programs.