01/12/1998 at 01:00 AM EST
JONATHAN LIPNICKI SQUEALS with delight as Bob Pflugfelder pulls onto the Warner Bros. lot of the 6-year-old actor's CBS sitcom, Meego (now on hiatus). Inside the former ambulance, since converted into a mobile lab called the Science Center, Pflugfelder, 30—a traveling tutor known to showbiz small fry as Science Bob—keeps microscopes, test tubes and dissecting kits. Today, his tool of choice is a hula hoop. Dipping it into an inflatable baby pool of suds he has placed in the parking lot, he forms a Lipnicki-size soap bubble to demonstrate the surface tension of water. "Mom!" the first grader shouts. "Catch me if I fly away!"
Pflugfelder, who also tutors tykes on ABC's Grace Under Fire and CBS's Everybody Loves Raymond, says the key is "finding how everything they're learning works in real life." Lipnicki's costar Michelle Trachtenberg, 12, for example, quickly grasps a lesson on cell structure when Pflugfelder likens the cell's nucleus to a director and its cytoplasm to a stage.
Raised in Westchester County, N.Y., by a stockbroker and a homemaker, Pflugfelder graduated from Boston's Emerson College in 1989 with a degree in TV production. "But my love was teaching," he says. After a stint as a grade-school science instructor in Boston, he moved to L.A. in 1995 and sold producers on his mobile lab to augment kids' daily three hours of study. Eventually, says Pflugfelder, who lives alone in Burbank, he'd like to turn the van into a building "people can visit, like the Natural History Museum." For now, he says, "when people ask, 'Where is the Science Center?' I say, 'It's in my apartment.' "