Before he joined the Boy Scouts, 11-year-old Damien Weiss of Arlington spent his weekends watching television.

"It was boring," said Damien, sporting a Tenderfoot badge on his shirt and a charcoal smudge on his face. "But now, it's just activities, activities, activities."

Thousands of youths and adults who felt the same way turned the Washington Monument grounds into a giant campground yesterday, demonstrating their scouting skills and accomplishments in a celebration of the 75th anniversary of the Boy Scouts of America.

The day-long "Diamond Jubilee Scouting Expo" was sponsored by First American Banks and drew more than 500 scouting units from the District, Northern Virginia and suburban Maryland. The spring weather and an assortment of traditional and not-so-traditional scouting activities entertained a festive crowd that U.S. Park Police said numbered about 37,000.

Scouts and their adult leaders turned out as early as 7:30 a.m. to begin building or setting up the log towers, monkey bridges, obstacle courses and other featured attractions. There were Indian dances, rope-tying lessons and demonstrations on how to cook in cardboard box ovens.

But, reflecting attempts to update the image of scouting, there were also computer exhibits, a space shuttle display, a wind-driven cooking spit and a skit on drug prevention.

"We have things here today that 10 years ago I wouldn't have conceived of scouts ever doing," said Paul R. Davis Jr., a scout executive with the National Capital Area Council, who presided over opening ceremonies for the expo at the Sylvan Theater near the monument.

Davis said interest in scouting declined in the early 1970s during what he described as a period of rebellion and disruption. These days, according to Boy Scouts of America officials, there are more than 4 million Boy Scouts and Cub Scouts nationwide, including more than 55,000 in Washington and surrounding jurisdictions.

Yesterday's expo stretched across the monument grounds, providing a sampling of scouting life.

In its midst stood Robbie Loveday, 16, a senior patrol leader from Hyattsville, who guided Troop 299 as it built an elaborate tower of logs held together by ropes rather than nails.

"We practiced twice this year," said Loveday. "We went to where they were clearing out woods to make houses, and they gave us some logs."

Though at least one tower seemed to have been commandeered by the adults, most of the troop leaders seemed content to let the kids have most of the fun.

"I'm turning around and giving back what's been given to me," said Richard Ellison, 24, a real estate salesman and former Eagle Scout who is now scoutmaster to Troop 667 in McLean.

He watched as Eric Gsell, 13, and Ron Thayer, 14, took their place in what Ellison described as "your basic business management production line" and busied themselves making sourdough donuts.

Chester Bigelow, 15, and Lonell Johnson, 8, both of Pack 307 in the District, showed off a collection of items the scouts had learned to make at their weekly meetings.

Used creatively, Bigelow demonstrated, a pine cone found in the woods can be painted and used as a decoration. Seashells become a necklace. A plastic cola bottle becomes a planter. And a hot potato container from a fast food restaurant becomes, by adding plastic flowers, a table centerpiece.

Johnson, who joined the scout pack two months ago, said he liked scouting because, "We go on trips and build things."

All of the scouting units set up exhibits that could be enjoyed by others.

Kevin Hilton of Annandale, for instance, had a great time climbing the wooden wall erected by Troop 1345 of Burke. The 13-year-old adventurer, a member of Troop 1533, said it was okay climbing up but "tricky" coming down.

"Some of the boards are real thin, and it's real steep," he said. "Coming down, you feel like you're going to fall, and you can't see your feet."

That was not a problem for the scouts who tried stilt-walking under the guidance of Bruce Redding, committee chairman of Troop 3 in Rockville. They kept looking down at their feet while Redding was encouraging them to look where they were going.

"Remember how you used to ride a bike, and how you could never get that thing steady," he said while balancing one youngster from behind the stilts. "And remember how, all of a sudden, it worked."

The scout, who went toddling unsteadily ahead, seemed to get the message.