The classic Doppler Shift , once taught through classroom drawings and static textbook diagrams, is now shown in its dynamic splendor as a sound wave from a car horn, ambulance siren, or other source shifts to a higher frequency when the source approaches and a lower frequency as it moves away. Brownian Motion , the principle used by Einstein to describe the activity of microscopic particles being bombarded by surrounding molecules, is presented via Java applet in a way that enables the viewer to follow the path of a single particle, and to adjust the mass ratio among the particles to see the effect. Fourier Synthesis , a method of electronically constructing a signal with a specific, desired periodic waveform, can be demonstrated with thousands of dollars of equipment - or online, available any time for the user, who can watch and listen to the changes each time he or she resets frequencies.

ePhysics home page (Martin Simon, UCLA)

These Java applets and Flash animations, which have been tested and shown to be effective in physics education, have been collected in one location -- the UCLA ePhysics web site ( ephysics.physics.ucla.edu ). "If a professor did a search for physics applets, simulations, or exercises, he would get thousands of hits, and going through and testing them all would be formidable," says Martin Simon, director of UCLA's Instructional Support Lab and creator of ePhysics. If good applets don't yet exist on a topic, Simon's group develops new ones for the ePhysics site.

Among those who are grateful for ePhysics is Claudio Pellegrini, professor and chair of UCLA's Department of Physics and Astronomy. "Unless you're an extremely good mathematician, equations don't tell you much," Pellegrini says. "Most people need to have a graphical representation - to change something and see the effect. This gives students a deeper understanding of the concept we're discussing, and an ability to intuit the physics of the problem, which is something that typically takes much longer to develop."

ePhysics is being used at both UCLA and UC Berkeley for lecture demonstrations and student use outside of class, through links set up on course web sites. With a new grant from the TLtC, Simon is currently working with collaborators at UC Berkeley to improve and extend the site, develop new instructional tools to meet the specific needs of other UC campuses, and assess the efficacy of the applets in educating students. Based on the response of the students who have already used ePhysics, the project has been a huge success. "The more ways students can see, hear, and manipulate concepts, the better the likelihood that these concepts are going to come across," Simon notes.

Animating Astronomy

In both physics and astronomy, the advantages inherent in information technology have proved irresistible to educators. The opportunity to incorporate more visual elements into undergraduate astronomy education motivated Roger A. Freedman, a UC Santa Barbara lecturer, to take the lead in developing a CD-ROM and companion web site ( www.whfreeman.com/universe/ ) for the fifth and sixth editions of the textbook Universe, of which Freedman is the lead author.

"Astronomy is so intrinsically visual, as well as being very complex," notes Freedman, who collaborated on Universe with a commercial multimedia educational firm, Sumanas Inc. "Anything you can do to simplify the visual elements we use in astronomy for students who are not familiar with those representations is very useful."

The Universe CD-ROM includes programs in which students can input different numerical parameters for graphs to see how they are re-drawn. Animations show the dynamic nature of galaxies. A commercially developed animated program called "Starry Night" acts as a planetarium simulator in which students can view the sky from any place in the solar system at any point in time, and includes instructions and exercises. "Many students have not spent a lot of time looking at the night sky, and so they're unfamiliar with the notion that the planets change positions with respect to the stars," Freedman says.

The animations in particular have brought clarity to the classroom concepts, Freedman says. One that has been especially helpful is the Hertzsprung-Russell Diagram and Stellar Evolution [ see animation ]. When presented in animation form, the standard graph - which shows the luminosity of a star on the vertical axis and its surface temperature on the horizontal - enables students to see how stars of different masses evolve over billions of years. Astronomers put great store in following these evolutionary paths. "This animation really brings home, for instance, the dramatic changes that have taken place in our own sun over the last 4.5 billion years," says Freedman. He is currently working on the seventh edition of Universe, which is being used by more than 100 institutions in the United States and Europe, including four UC campuses.

Counting the Galaxies
UC Davis physics professor Andy Albrecht wanted to convey a complex but critical mathematical formula to students in his Cosmology 10 course. He worked with his campus's educational technology group, MediaWorks, to develop a simulation called "Galaxy Counter," which teaches Albrecht's students - most of whom are non-science majors - how to quantify the clustering of galaxies. It's the type of analysis that is at the heart of understanding cosmological revolutions.

"If we want to test theories about the evolution of the early universe, we need to be able to undertake systematic comparisons of data on how galaxies are clustered with the data suggested by these theories," Albrecht explains.

Galaxy Counter
( http://www.physics.ucdavis.edu/Cosmology/COS10/GalaxyCounter/index.htm ) presents various galactic images and then visually demonstrates how astronomers convert them to numbers. "The actual formulas are really too complicated to teach in a general education class, but when presented visually, students can begin to see the essence of what we're doing, which is very intuitive," Albrecht says. "They can fiddle around with it, explore the technique on their own, and all of a sudden they own it."

Most scientific concepts are best taught through such active exploration, Albrecht notes, but in the past, giving undergraduate students hands-on experience with scientific tools has often not been feasible, for reasons that include the large number of students, the expense of the equipment, and the inability of instructors to spend enough individual time with students to bring them up to speed. With a computer model such as Galaxy Counter, students can learn the same concepts without any initial expertise. "We can and do lecture about this as well," says Albrecht, "but this is a much better way to learn, and it's also closer to the way scientists actually work.

Galaxy Counter (Andy Albrecht, UC Davis

Hands-on Universe
Students in K-12 schools are also getting the opportunity to experience astronomy firsthand, thanks to computer technology. An idea born at a professional meeting in Hawaii in 1992 blossomed into Hands-on Universe ( www.handsonuniverse.org ), a web-based educational program used by hundreds of middle- and high school teachers in the United States and abroad.

"Typically, these students are taught about science, rather than how to do it, and it becomes memorization and rote," says Carl Pennypacker, a research astronomer and educator at UC Berkeley who developed the program. "We wanted to teach a conceptual understanding of science by having students actually undertake scientific activities. Students learn best by doing it."

Hands-on Universe users can request observations from an automated telescope located at the University of Chicago's Yerkes Observatory, download previously obtained images from an extensive archive, and analyze them with the assistance of image-processing software. Eventually, more telescopes will be employed and students will be able to remotely access a wider variety of images.

"Astronomy data is so amenable to network-based distribution," says Pennypacker. Among other things, K-12 teachers are trained in how to "subtract" old images from newly available images of asteroids, supernovae, and other cosmological phenomena. These subtractions, characteristic of astronomers' work, leave only the differences between the new and old image.

Hands-on Universe has proved to be an unqualified success among students, who have found objects as far away as between the orbits of Neptune and Pluto. "Students and teachers just love the astronomy data, because it's so beautiful," Pennypacker says. "We're letting them see it, and ultimately we want them to be able to design and experiment, undertake it, write it up, and have it evaluated by their peers - the epitome of the scientific process."