School For Thought

Perched atop laboratory stools, eight students in Freda Hill's 7th grade science class are swapping notes about their field trip the day before to a local steam-heating plant. "The Ashley Street plant has been operating since 1988," says a small blond girl. "It was called a trash energy facility, but at the time, there were a lot of problems with environmental systems." Another girl volunteers that the pipes carrying water to the plant are 22 miles long and 2 feet in diameter.

And so the conversation about the facility goes, with each student offering another scrap of information. Each time someone speaks, heads bend and students scribble intently in their notebooks. Along the way, the group discusses the "opacity" of smoke, the mathematics of converting water to steam, and the three forms of oxygen. Upon completing a thought, pupils call on classmates to take up the discussion. Their teacher sits silently, her arms folded across her chest, taking it all in.

Then the group runs into some confusion. One student says the prefix "milli-" means 1,000, and another says it means 1 million. "What is your math?" Hill interjects. When the students seem unsure, she adds: "We need to clear that up. Maybe we can e-mail...