LOS ANGELES — Jake Zeiss bolts from his west LA bungalow before 8 a.m., red hair damp and shirttail flapping.

After seven hours of back-to-back meetings, he volleys for an hour with his tennis pro. Still perspiring, he slides back into his Mercedes, gobbles a nutrition bar and does paperwork on a lap desk while his chauffeur burrows through the nation's worst rush hour traffic.

Jake Zeiss is 9 years old. His paperwork is multiplication tables.

He gropes for a pencil that has dropped down the dark, sticky crevasse of the back seat. And he's tempted by a new yo-yo. It's the kind that beeps and lights up.

"Jakey, is that a good use of your time?" hollers his mother, Kim, as she swerves past a loafing Honda. "How many problems have you done?"

The Zeiss family is late for hockey practice. After that, it's fencing lessons for Madison, Jake's 10-year-old sister. Their father, Gary, will meet them at the gym — hopefully by 8 p.m.

Kim Zeiss has transformed her SUV into a rolling Wal-Mart, with cases of snacks and drinks buried beneath backpacks and sports equipment piled so high she can't use the rearview mirror.

"Fortunately, the kids don't get carsick," Kim quips. "If that happened, we'd be sunk."

The Zeiss family might be insanely busy, but they are not alone.

Scientists at UCLA have spent the past four years observing 32 Los Angeles families in a study of how working America somehow gets it done. Day after day.

The UCLA Center on Everyday Lives of Families is one of six long-term projects sponsored by the Alfred P. Sloan Foundation examining the intersection between family life and work.

At UCLA, a team of 21 researchers has completed the $3.6 million data-collection phase. A second phase will be devoted to analysis and, researchers hope, influencing federal policy on family issues.

Already, trends are emerging from their observations, and they appear to be related to the biggest change in family dynamics since Kim and Gary Zeiss were kids themselves:

Mothers working outside the home.

It's a poorly-understood seismic shift in both the nation's economy and daily life. For some families in the study, it allows them to own a bigger house, drive better cars and take nicer vacations. For many more families, two paychecks are necessary to put food on the table.

It means parents and children live virtually apart at least five days a week, reuniting for a few hours at night. In this study, at least one parent was likely to be up and gone before the children awoke.

When they are together, today's families tend to stay in motion with lessons, classes and games, or they go shopping.