Julian Smith, executive director of the Cooper River Bridge Run, was helping Christine Osborne set up tables and chairs at her booming Wonderfest event last June when an idea stuck like cotton candy on a jump castle.

Where: Hampton Park

When: 11 a.m.-6 p.m. Friday

Race start: 5 p.m.

Cost: $10 for T-shirt and race number (children may also race for free without a T-shirt)

Parking: Lots near Stoney Field on Fishburne Street with shuttle transportation available

More info: www.bridgerun.com

Kids Run & Wonderfest

“Julian saw we had 4,000 people having so much fun,” Osborne said. “He said, 'This is awesome, but it's getting so big you're going to have to do something. Why don't you join our Kids Run?' That's when the light bulb came on.”

The Cooper River Bridge Run Kids Run is a one-mile race around Hampton Park the day before the real thing. Wonderfest, the brainchild of Osborne and staffs at her four Wonder Works toy stores, celebrates the talents of Lowcountry kids while supporting charities, some of them run by children.

The magic merger at Hampton Park from 11 a.m. to 6 p.m. on Friday gives children 13 and under a chance to mix fitness with what Osborne calls “the Lowcountry's largest free family festival.”

Yes, free “crazy hair” and a free Wonder Works toy for each kid, with items donated by national toy companies.

“We're keeping the toys kind of a secret right now,” Osborne said. “But I can say that they will be fun.”

Bi-Lo will provide free hot dogs, snacks and water.

Runners 13 and under get a T-shirt and race number for $10 with race-day registration at Hampton Park) for the 5 p.m. race. Children may run free of charge without a T-Shirt.

Registered runners also receive a medal and coloring book. Adults can participate, too ($12, including T-shirt).

Wonderfest perks include pony rides, Mad Science exhibits, live entertainment, play zones, face painting, a Webkinz van and a mechanical bull. The Monster Mobile Game Theater will broadcast Wii Fit and Zumba on three 55-inch screens.

The activity theme continues with rock climbing and an obstacle course.

Wonderfest started as a benefit event, and this year the charities include Hugs for Harper, Keys for Hope, Happy Wheels, Abby's Friends and MUSC Children's Hospital.

“This is history in the making,” Osborne said. “There is no other run in the nation that does something like this. It's going to be incredible.”

Parking is available around Hampton Park. Shuttle transportation will be provided from lots near Stoney Field on Fishburne Street, Osborne said.

With most Lowcountry children out of school for spring break, Osborne expects a turnout “between 7,000 and 10,000 people.”