|Techie Jim Lehman offers students a different picture of reality.|
Not long ago, science teacher Jim Lehman found the solution to a high-tech problem in the plumbing section of his local hardware store in Richmond, Va. In Lehman's classes, students use computer software to manipulate, enhance, and analyze a wide range of images. The technique is called image processing, and it's pretty advanced science for teenagers. But rather than buy or cadge the required digital pictures, Lehman wanted his students to produce their own. He just needed to find some way to hold the lens of his digital camera snug against the eyepiece of a microscope.
"I tried to empty my mind of preconceptions," Lehman recalls. And that led him to the hardware store's plumbing aisle, where he found an adapter designed to connect plastic pipe with metal. One end of the adapter had a rubber sleeve that gripped the camera perfectly, and the other end fit nicely onto the microscope. It did the trick. Held steady in the adapter, the camera could be used to photograph minute crystals, bacteria, or planaria. It even worked with a telescope, allowing his students to record the sky's celestial wonders.
The find was particularly satisfying. The quality of the images from his $100 camera rivals the output of scientific cameras that cost thousands, Lehman says. Even more significant, his students' work took a quantum leap in sophistication: Instead of analyzing purchased digital images, they generated their own from projects and experiments, just like real scientists.
Such feats of ingenuity are a Lehman trademark, says JoAnn Mulvany, the director of the Science, Mathematics, and Technology Specialty Center, the Henrico County magnet school where Lehman teaches. Like many practical scientists, the 40-year-old Lehman is a tinkerer to the bone, Mulvany says.
His camera innovation has already given new life to the school's "global sand lab." Students now make their own digital pictures of sand samples from different parts of the world and analyze them with the image-processing equipment. Comparing granules on a computer screen, they can see for themselves how, say, quartz and magnetite sands differ.
Image processing is something scientists have been doing for years. Medical technicians, for example, process images when they do ultrasound tests on patients.
According to LuAnn Dahlman of the Tucson, Ariz.-based Center of Image Processing in Education, the technique works something like this: When a picture is digitized, each element--or pixel--in the picture is assigned a numeric value. That value may represent brightness, temperature, elevation, or some other measurement that the researcher wants to examine. Each pixel is colored, with the shade determined by its numeric value.
Using the digital-processing software, researchers can bring out previously undetected features or patterns by adjusting the pixel values and display colors in the digital image. "Image processing does not use the computer as a 'viewer' but as a tool to make measurements and analyze data," Dahlman explains. "Students manipulate digital images in order to emphasize specific features, explore patterns, and visualize processes."
Dahlman, Lehman, and other image-processing advocates believe the technique is loaded with power to boost student interest in science and technology. As Dahlman puts it: "Students' learning time is spent using higher-order thinking skills, actively interpreting and evaluating information rather than passively absorbing it."
Lehman uses image processing in his earth-science classes, a course he teaches on research tools, and an interdisciplinary course that combines physics and astronomy. Indeed, the technology is the centerpiece of all his classes. Students work on projects and experiments that both he and they design. This kind of project-based learning, Lehman points out, can be particularly challenging for teachers, as there is no textbook to fall back on.
Lehman is especially proud of a project he designed to measure levels of carbon dioxide pollution. He had youngsters from different neighborhoods bring in leaves from the same type of tree. They photographed the tiny stomata, or pores, on the underside of the leaves through a microscope. Gases and vapor that nourish trees pass through these stomata. Leaves of trees that grow amid heavy concentrations of carbon dioxide, however, have fewer than those that grow in cleaner air. After some tweaking with the image processor, the students could count the stomata of various leaves on computer screens and identify the most polluted parts of town.
Lehman first became interested in science while growing up in Virginia's Shenandoah Valley, where his father taught college physics and astronomy. "As a child," he remembers, "I watched eclipses and meteor showers."
|Image processing—a hard-core scientific tool borrowed from the National Institutes of Health—is the centerpiece of Lehman's classes.|
He spent the first seven years of his career teaching earth science at a middle school in Virginia's rural Hanover County. But he quickly became fed up with textbook exercises and lab activities. They were too pat. To shake things up, he turned to the computer as a classroom tool to teach his students how to use spreadsheets to analyze data from experiments. About this time, he and a colleague, working with statistical-modeling software and topographical maps, began predicting possible changes in flooding patterns caused by the effects of global warming.
Then he heard about image processing. Hoping to make earth-science activities more interesting for his students, Lehman tried some "bare bones" processing. But the technique required equipment his school could not afford or access.
But in the late 1980s, the National Institutes of Health introduced powerful image-processing software that would run on personal computers. NIH made it available to the public free of charge, and a team of teachers at the University of Arizona began writing classroom applications. Lehman learned about the software during a two-year sabbatical at a science-education center run by the city of Richmond. "I got thoroughly addicted," he says.
Lehman attended training programs on NIH Image, as the software is called, and eventually became a certified teacher-trainer through Dahlman's group. Such expertise led the Henrico County district to hire the lanky Virginian. The system plans to introduce the technology in all its schools over the next two years, and Lehman is slated to play a key role: He will be one of the people showing teachers how to use image processing in their classrooms. Around the district, he's already earned the nickname "ET"--esteemed trainer.
But even for esteemed trainers, things don't always go as planned. During a recent introductory lesson to 20 9th graders, Lehman was distracted by a student with a software problem. When he turned his attention back to the class, he discovered that some students had forged ahead on their own: Several had used the software tools to gouge the eyes out ofa digital portrait of the Mona Lisa, the test imagefor the exercise. Others had zoomed in on her breast.
Lehman flipped on the lights and marched the students back to their regular computer-less classroom. He was both mad and disappointed. He'd planned to have the kids start creating fictional continents, a project he knew they would love. He was going to let them use image processing to design the topographical contours of the land. But that would have to wait.
Back in the classroom, he chewed them out. "We don't have to use the computers," he told them solemnly. "We can just read the book."
Tough words. But coming from Lehman, the students knew it was just a bluff.