B. A "Less is More" Approach Towards Science

Narrator: This is Science Today. When it comes to learning about science, students do best studying fewer, but more in-depth topics - rather than trying to learn several topics at once. Marcia Linn, a professor at the University of California, Berkeley's Graduate School of Education, says the more in-depth learning approach adopts the decades-old notion - that "less is more."

Linn:We discovered that it was typical for students to have a new topic, like genetics or heat and temperature or electricity or mechanics every single week in middle school. And we just couldn't imagine that they would be able to master anything under those circumstances.

Narrator: In a 15-year study, Linn discovered science students not only retained more with a well-planned, in-depth curriculum - but that they became better lifelong learners.

Linn: It seems clear that if you don't have any experience of what it means to understand something in-depth, it's going to be very, very difficult to actually ever learn something in-depth in the future - or to be a lifelong science learner.

Narrator: This deeper coverage approach has already been adopted successfully in countries such as Japan and the Czech Republic. For Science Today, I'm Larissa Branin.

C. Lunar Meteoroid Impacts Prove Insightful to Earth's History

Narrator: This is Science Today. By dating tiny droplets of molten rock scooped up from the moon during the 1971 Apollo 14 mission, researchers have come up with a new chronology of the Earth's history. Paul Renne, a geologist at the University of California, Berkeley says the molten rock, which resemble tiny glass beads, were the result of violent meteoroid impacts on the moon billions of years ago that created huge craters on its surface.

Renne: It's pretty clear that the really big impacts that would've been the most destructive to life on Earth or anywhere else, occurred early on.

Narrator: But Renne's group discovered evidence of another peak of cratering activity about 500 million years ago. This coincides with the "Cambrian explosion", a period in which life on Earth dramatically diversified.

Renne: So clearly, turning up the cratering rate doesn't snuff out life - if anything it seems to stimulate it, if there's a causal relationship there. It may be just coincidence, but it's certainly a striking possibility.

Narrator: For Science Today, I'm Larissa Branin. .

D. The Latest on the Triana Mission

Narrator:This is Science Today. NASA's Triana Mission, which will help scientists construct more accurate models of the Earth's climate and energy balance, has recently received enthusiastic support from White House Science and Technology advisor, Neal Lane. The development of the Triana mission is led by Francisco Valero, who directs the Atmospheric Research Lab at the University of California's Scripps Institution of Oceanography.

Valero: The scientific of Triana is to observe the Earth from deep space, which is very different from what we had been doing so far. We will increase the accuracy of our observations, we will have simultaneous observations and we're able to see the whole thing and very importantly, we are not scanning - the Earth is rotating and processing in the field of view of Triana.

Narrator: Images of Triana's view will also be available over the Internet for educational purposes.

Valero: We are getting students involved at all levels. K to 12, undergraduate and graduate students, so the whole range of students are involved in the project.

Narrator: Triana is set to launch in January 2001. For Science Today, I'm Larissa Branin.

E. Using Plants to Get Rid of Toxins

Narrator: This is Science Today. For years, trichloroethylene (or TCE), a chemical widely used in industry as a degreasing agent or solvent, was disposed of directly into the soil. As a result, there are literally thousands of sites contaminated with this toxic compound. Thomas Wood, a chemical engineer at the University of California, Irvine, has been working with genes that enable bacteria to degrade TCE.

Wood: We first thought it would be best to strip the trichloroethylene out of the soil by passing air through the soil and treat the trichloroethylene that was removed from the soil in this air stream in an above ground reactor.

Narrator: This was too expensive, so the researchers are using plant roots as the reactor system. This has proved a more popular move.

Wood: Because this is the probably least expensive way to remediate these kinds of compounds. People are familiar with bacteria in terms of septic tanks and they're very accustomed to seeing bacteria get rid of waste and so they're much more likely to welcome this kind of a system versus something like incineration.

Narrator: For Science Today, I'm Larissa Branin.