Family budgets might still be tight, but summer fun abounds at the Oakdale Discovery Center, where several educational and aerobic activities for all ages are offered at no cost.

The center's 220 acres of prairies and trees provide the backdrop for guests to go on bike rides, hunt for treasures and play a round of chess, checkers or tic-tac-toe, using life-size pieces. All equipment is provided. Patrons, who don't have to be Oakdale residents, can check it out by presenting a photo ID.

"We want families to get out and enjoy the park," said recreation supervisor Julie Williams. "This is the hidden gem of the city and people didn't know we provided that."

Oakdale used a $4,000 Statewide Health Improvement Program grant from Washington County to buy two tandem bicycles last year, and they've been getting lots of use. "We had people here in March, even with ice on the sidewalks," Williams said.

Another popular item has been Nordic walking poles. The poles, which look like ski poles, allow walkers to get cardio exercise while building strength in upper torso muscles. Nordic walking can produce up to a 46 percent increase in energy consumption compared to walking without poles, according to the Cooper Institute, a nonprofit research and education organization that studies the role of exercise in preserving health.

A keen sense of direction with the help of a GPS unit will be needed to find 15 caches in the Discovery Center or other Oakdale city parks. The center has two units for high-tech treasure hunting.

For a more traditional experience, try the "Nature Hunts." The scavenger hunt asks guests to find things such as feathers, cattails and unusual shaped leaves. The exercise also guides participants to search for -- but not touch -- bird nests, caterpillar, worms, spiders and webs.

Naturalists or those at heart can check out a Discovery Backpack and go bird watching or look for deer, fox and raccoons that roam the preserve. The packs come with binoculars, field guides, nets and other equipment allowing guests to get close to nature.

This summer, the Discovery Center will offer free seminars as part of its Amphitheater Speaker Series. Those begin on June 16 with a presentation by the University of Minnesota Raptor Center. Others include sessions on health myths on June 28, weight loss on July 26, beekeeping and honey extraction on Aug. 21, and stress management on Aug. 23.

Or just go for a walk. The preserve has paved and grass trails with varying degrees of difficulty.

Tim Harlow • 651-925-5039, Twitter: @timstrib