Organizers called yesterday's Invent America! exposition a proud demonstration of students' "analytical thinking" and "creative learning" abilities.

But Shane Pielli, 14, said his invention was the product of nothing so high-falutin: He merely was interested in devising a way to get his mom to stop nagging him about opening and closing the window blinds.

"My mother was always telling me to 'close the blinds because the sunlight is bleaching the furniture,' or 'open the blinds because we don't live like vampires,' " explained the Sandpoint, Idaho, eighth-grader. "So I decided to do something about it."

Shane built a gadget that uses a light sensor to automatically open and close a set of blinds. His machine was on display yesterday, along with inventions by 47 other youths deemed regional finalists in a national competition for young inventors.

The exposition at Freedom Plaza, at 14th Street and Pennsylvania Avenue NW, was sponsored by Invent America!, a nonprofit arm of the U.S. Patent Model Foundation. It is a prelude to an awards banquet Thursday at which nine students -- one each from kindergarten through eighth grade -- will receive awards worth $1,000 in saving bonds for their projects.

"We started annual competitions in 1987 out of a concern that only about half the U.S. patents being issued these days are being issued to Americans," said spokeswoman Audrey Bergin Smith.

The competition was designed to "foster analytical thinking skills among students," added Nancy Metz, Invent America! executive director. "This kind of creative learning will hopefully teach them how important innovation is in our society."

Many of the inventions on display yesterday were inspired by everyday problems. Rachel Price, 12, drilled small holes in the lip of a paint can to reduce spillage because she "saw what a mess my dad made when he was painting."

Andrea Ponton, 8, conceived the idea of using clear-plastic pipes in homes after her aunt "dropped a ring down the drain and we never found it again."

Rachel Hostetler, 10, came up with a "fuel beeper" that alerts a driver if the gas cap hasn't been replaced after a fill-up.

Some inventions were more whimsical. One popular invention among the assembled inventors was Matt Nissen's bike board -- a bike frame welded to a skate board.

"You can glide longer than a bike, you never get a flat, and my friend and I have never been hurt in an accident," boasted Matt, 13.

Inventor Byron Myers, 14, couldn't help marveling at all the swell ideas on display.

"It's kind of neat to think there's still a lot of improvements that can be made in this world where everything is so high-tech and modern," the Kansas City, Mo., eighth-grader said.

Inventor Jonathon Merickel, 10, said he liked Matt's bike board about as much as his mouth watered for Sarah Cole Racine's "food tape," an edible substance dispensed like tape that can be used to hold burritos and other messy foods together.

But asked to name his favorite invention, Jonathon didn't hesitate to name a product that could make the pro-American sponsors of the contest cringe.

"Nintendo," he said.