Smart Enough for a Fifth-Grader
Imagine, said UVA Associate Professor Jerry Floro, if you could ride an elevator for two days – up, up, up – 22,500 miles to a space station or satellite orbiting the Earth.
Fifty sets of fifth-grade eyeballs popped at the notion. No elevator cable in existence today could support that kind of ascent, Floro told the children. Carbon nanotubes – super-strong cylinders of carbon atoms – might make such a feat possible.
With that introduction to the way-cool world of nanoscience, the Broadus Wood Elementary School students scrambled to visit nine demonstrations set up around their cafeteria, manned by Floro’s Materials Science and Engineering Department graduate students. For several years, Floro has been offering “NanoDays” demonstrations to local elementary schools on a volunteer basis, feeding his passion for getting children interested in science in general and engineering in particular. A bonus is that Floro’s students get to practice a very important skill: talking about science and engineering in a way that is understandable to the general public.
Ph.D. student Begum Unveroglu showed the fifth-graders how a pinky finger-sized portion of white hydrophilic powder could absorb far more water than a sponge.
“What would you do with this type of material?” Unveroglu asked the children.
“Maybe use it in a flood?” one fifth-grader theorized.
“How about a baby diaper?” Unveroglu said.
Two tables down, Ph.D. student Lavina Backman taught the students the opposite phenomenon – hydrophobic materials repel water. She used doll clothes to illustrate what happens when water hits fabric that isn’t treated with a fluid-resistant material, compared to the way the water beads and rolls off fabric treated with a hydrophobic material.
No fifth-grade science demonstration would be complete without Oobleck, the mixture of water and cornstarch that behaves like a gooey, liquid slime when it is left alone, but becomes a solid when it is subjected to pressure. Ph.D. student Matt McMahon wasn’t going to leave it at a cheap thrill involving kids and goo, however. The scientific term for Oobleck, he taught the children, is “shear thickening” material.
“When you move your hands really fast,” he said, as he shaped the Oobleck into a rock-hard ball, “you start jamming all the particles together, and they don’t like it, so they resist.”
At another table, a fifth-grader was startled when Ph.D. student Patrick Steiner gave him a metal spring and encouraged him to pull it apart. Wouldn’t it be broken? Nope, Steiner said. This was a special type of metal. In a cup of hot water, the spring shrunk back to its normal shape. “When you get down to the atomic level of metals,” Steiner said, “you can change their properties.”
Ph.D. student Eric Hoglund had students don adult-sized oven mitts and try to assemble Legos. That’s an approximation of how difficult it is to build anything out of nano-sized materials. And that is why scientists are working on ways to use particle and chemical science to make materials that can assemble or repair themselves, Hoglund said.
At Ph.D. student Xiaopu Li’s table, students learned the possibility of seeing nano-scaled structures by “touching them” with a very sharp point; Ph.D. student Andrew Cheung showed how the arrangement of particles in butterfly wings can affect the way the light is reflected off of them, and hence their color; master’s degree student Allison Popernack demonstrated ferrofluid – magnetic fluid; Ph.D. student Katie Lutton taught the students about surface area.
At the end of the demonstrations, the children sat cross-legged on a rug, and Floro quizzed them on what they’d learned. They remembered the difference between hydrophilic and hydrophobic, and impressively remembered “shear thickening.”
“I hope you learned something today,” Floro said, “and if you liked it, remember that you could be a nanoscientist one day, too.”