Darrell Sapp, Post-Gazette Theresa Kennedy, 10, a fifth-grader at Prospect Elementary, laughs as she touches a Van de Graaff generator yesterday during Chemistry Day at the Carnegie Science Center.

The old way of teaching science had students listening to long lectures from gray-haired men in white coats.

These days, more teachers are embracing the idea that science is not really about memorization, but understanding big ideas.

"We know now that we can't tell kids enough science fast enough to keep up with today's science knowledge," said Janet Kahan, a science teacher from Plymouth, Mich. "What we have to create are science-thinkers."

About 250 science educators from across the country are holding their annual conference this week at the Sheraton Hotel in Station Square to compare notes on creating a new kind of science classroom that relies more heavily on hands-on learning to spark inquiring minds.

They're advocating a major overhaul of the way science is being taught in public schools so that students will be more able to excel when science is added to state standardized tests that measure student achievement.

Pennsylvania will start requiring students to take a standardized science exam in grades 4, 8 and 11 in 2007-08. A voluntary field science test will be offered to school districts in 2006-07.

Under the federal No Child Left Behind Act, schools are required to test elementary, middle and high school students in science. However, unlike the required math and reading tests, the results will not be used to determine whether the school has made adequate yearly progress.

The gathering of nationally known speakers and science educators, called "The Next Step Institute," is hosted by ASSET Inc., a local nonprofit organization that supplies 48 school districts in Western Pennsylvania with professional development and science learning kits. The conference started Wednesday and ends today.

"This is a major movement in science education," said Reeny Davison, executive director of ASSET: Achieving Student Success through Excellence in Teaching. "Students are learning more, and teachers are teaching better because of the national network."

Tom Peters, executive director of the Association of Science Materials Centers, a nonprofit group representing those who deliver science materials to elementary and secondary schools, said the style of education in public schools must change to reflect the changing employment opportunities in the workplace.

"Our challenge as science teachers is to rethink, reinvent and redefine the way science is taught in our schools," Mr. Peters said. "That's why we're here.

"A lot of schools are still teaching science the old-fashioned way with textbooks, worksheets and reading about science, not doing science," said Karen Ahearn, a spokeswoman for ASSET.

Carrie Betters, a first-grade teacher at Allegheny Early Childhood Center, said the conference has opened her eyes to new ways of integrating science into other subjects.

"In the first grade, we focus on basic skills and what science is," she said. "We learn how to explore, observe and how to use scientific tools. The ASSET kits are all hands-on, so it's fun. Kids really enjoy touching and manipulating things."