BYNUM -- Most fourth-graders who belong to the indoors generation haven't had much soil on their palms or muck on their sneakers.

That's why the Haw River Assembly, a nonprofit preservation group, wants children to put a little dirt in their day.

For 17 years, the assembly has taken fourth-graders living in the Haw's watershed down to the river. There, children see the gurgling rapids that feed their water supply and the crawly creatures endangered by pollution.

"Many of them have only seen rivers from cars going over a bridge," said Elaine Chiosso, director of the assembly. "You have to see the river up close to understand it."

There are three sites on the Haw River that roughly 1,500 students from Durham, Orange, Chatham, Alamance, Guilford and Rockingham counties will visit in the next three weeks.

Students will explore riverbanks in Alamance County's Saxapahaw and another site in southern Rockingham County.

On Wednesday, about 150 students went to Bynum, a former mill village in Chatham County.

At science stations set up along woodsy paths, volunteers taught children about stormwater runoff, water-dwelling insects and even pottery.

Dealing out mud clods from a plastic yogurt tub, volunteer Kira Dirlik showed students from Durham's Montessori Community School how clay is made.

Dirlik mixed in water and passed out handfuls to students sitting on a tarp. Under her watch, each mashed out a small clay cup, some with handles.

Dirlik, a longtime volunteer with the River Learning Celebration, has sometimes encountered children reluctant to play with mud. Especially those dressed in white.

But she and other volunteers said the reticence usually fades.

"These city kids blow me away. Spider webs and things are freaky to them," said Elia Bizzari, another longtime volunteer. "But later, most of the kids get into it."

Count 8-year-old Katie Golding among them.

Initially she was scared to join her classmates on stepping stones rising out of a shallow portion of the river.

"I don't play outside much," Golding said.

Minutes later she was over it, hopping from one sun-dappled rock to the next. Nearby, a much-bolder Carolina Friends School student lifted a spiral shell from the water.

Part of the assembly's mission, Chiosso said, is instilling environmentalism in a generation that eventually will shape policy.