The din of excited voices, interrupted by sound of plastic cups slapping on tables, washed over Auburn High School’s gymnasium Saturday.

More than 170 children from nine school districts competed in a daylong sport-stacking competition that’s fun and helps build coordination, physical education teachers said.

Hana Mizoguchi of Auburn’s Chinook Elementary School can attest to it, sort of. She’s 10 and has been speed-stacking 6-ounce plastic cups for a couple of years.

“It helps me with basketball, with my free-throw shots,” she said.

“I don’t really know how. It just does.”

Lisa Mason, a Chinook elementary physical education teacher, elaborated: Stacking and unstacking the cups at high speed helps students improve hand-eye coordination.

Because they have to use both hands, they also learn how to use both sides of their body, she said.

“It helps with basketball, typing, playing the piano,” among other things, Mason said.

John Ansotigue, a physical education teacher from Evergreen Heights Elementary School in the Auburn district, persuaded school officials to use speed-stacking as part of its physical education program, said Superintendent Linda Cowan.

The activity also helps children understand sequences, an important element in learning to read, she said.

“It supports what we are doing academically,” she said.

Elementary students and even some older students raced against time and each other Saturday. They unstacked 12 plastic cups that were slipped inside one another. They quickly made pyramids, often with three or six cups, and then restacked them.

Their hands and cups made a blur as they worked rapidly through the sequences. More than 100 people watched from the stands.

“I have to concentrate,” said Nickolas Dimisillo, 9, of Renton’s Highlands Elementary School. “I really like moving them really fast and not fumbling.”

Makena DeLappe, a student in Rock Creek Elementary School in the Tahoma District in Maple Valley, sprained her ankle last week and had to use crutches, but the 11-year-old insisted on participating in the tournament, said her teacher, James Main.

Makena said she practiced all week.

“It helps me with my hand-eye coordination and my friends are all here,” she said.

Ansotigue, Saturday’s sport-stacking tournament director, said he introduced the activity in a Renton School District classroom in 1994. Last year, he directed a smaller Auburn School District tournament that drew 118 kids.

Saturday he coordinated a larger event, the 2006 Washington State Sport Stacking Championship. The tournament included students from as far away as Quincy in Grant County and Stanwood in Snohomish County.

Ansotigue said the activity has its own organization, the World Sport Stacking Association. Stackers range in age from 6 to 17 and stacking now attracts more than a million children worldwide, he said.

“The kids are so excited,” he said. “It’s a good self-esteem booster. To me, that’s what it’s all about.”