The sidewalks of Logan Square were filled with science fans and lined with experiment-filled tents Saturday for the Science Carnival on the Parkway, part of the 10-day Philadelphia Science Festival.

More than 125 sponsors, including schools and organizations such as the event's presenting sponsor, Dow Chemical Co., filled the tents with scientific spectacles.

Mayor Nutter joined Dow president and chief executive Jerome Peribere as he announced the company would contribute $100,000 for next year's festival - and double the donation if other sponsors matched it.

"All the improvements which are going on right now are thanks to science," said Peribere, adding that he was happy children could see "that science is fun."

Peribere heads Dow's advanced-materials division, the umbrella group of the Philadelphia-based Dow specialty-materials businesses.

After addressing the crowd, he headed to the Dow tent to participate in and talk about some of the experiments his company had on display.

"This is the perfect place and the perfect time to talk about science and get young people actively engaged," Nutter said from a stage in front of the Franklin Institute.

The festival, which opened Friday, features a communitywide celebration of science including lectures, debates, and hands-on activities.

Adam Piazza, a 24-year-old "science interpreter" at the Franklin Institute, was in the crowded street, assisting with exercises involving smoky liquid nitrogen.

"Education isn't always in the classroom, it's everywhere," Piazza said. "Whether you hold their attention for five minutes, 30 minutes, or an hour, it's always amazing seeing what they get out of it."

While Piazza and his partner fired their liquid-nitrogen-powered cannon several times in the afternoon sun, other groups conducted quieter experiments in the shade of their tents.

The Harriton High School Science Club drew praise from several perusing the event, including Daniel Lofaro, a 28-year-old Harriton alum.

"It's the same type of thing I did when I was at Harriton," Lofaro said, "and they're doing it 10 times better now."

Lofaro, a Ph.D. candidate at Drexel University, attended with two former college classmates, Liz Henning, 25, of Delaware County, and Caitlin Locey, 26, of Center City. Each is in the science field, and they recognize the festival's positive impact on young minds.

"As science geeks and science professionals, this is a nice way to expose youth to science," Locey said.