In the fall of 2008, as I was gathering parts and writing software for the rudimentary spectrometer at the University of Illinois at Urbana-Champaign (UIUC) to take to Vietnam National University of Science – Hanoi for the Chem 420 class, I started working with the EnLIST program. EnLIST sought to assist Illinois high school teachers in becoming more effective in the classroom, and they looked forward to training their first cadre the following summer. Teaching assistant Kathleen Kelley was assigned to help prepare the labs. We decided to also use the spectrometer with the EnLIST participants. My “single use” rudimentary spectrometer, originally dreamed up for one-time use in Vietnam, had additional users even before the first mock-up was completed.
We needed to figure out how to connect a battery to the LED light source. Kelley went to the Electrical Engineering storeroom to select a battery and battery holder. She returned with a lithium button battery just the right size so that friction would hold the LED in place. “Brilliant! One less part to worry about, and we don’t need to solder!” I said. The internal resistance of the battery and the exponential response curve of the LED just balanced, giving a stable light source.
By April 2009, I had prototype software running to interpret the JPGs from the rudimentary spectrometer. A key contribution was that of UIUC Chemistry Professor Emeritus Stan Smith, one of the originators of computer-assisted instruction. Because we couldn’t trust how the cameras would line up with the spectra, the students had to tell the software where the data lay. “How do I extract data situated at an angle?” fussed and thought, and then asked Smith for advice. Drawing the problem on a white board, I showed Smith the image rotation problem. Smith put up his hand at an angle and twisted it straight. “Just rotate the picture until the line you’re trying to extract starts at a known place, going in a known direction,” he said. In the blink of an eye, the problem was, in principle, solved. After a few days of programming, semi-automatic data extraction was a reality.
As I prepared to leave for Hanoi, I wasn’t sure if I could take the lithium cell batteries by air to Vietnam. After a bit of inquiry, including talking with personnel at American Airlines and the Transportation Safety Administration, it appeared that as long as the batteries were in their original packaging and in carry-on baggage, it was permitted. I took an additional step: after I received the parts, I didn’t open any of them to check that the right items had been received, I just put them in my carry-on so the original packaging was intact. Included were linear diffraction gratings, 1 cm plastic clear cuvettes, photocopies of the baseplate design on cardstock, batteries, and LEDs.
In May 2009, I went back to Vietnam to teach Chem 420, Instrumental Analysis, to the same undergraduate K51 class who took Chem 222 the year before. But this time, Vietnamese faculty had already taught much of the class content. Students were to present lectures; I gave only one lecture per day, and there were daily in-class projects, allowing the students to teach themselves. In many ways, with so much active learning, it was the best large-class teaching I ever did. Nguyen Thi Thai, one of the HUS faculty, videoed many of the lectures. It was not at all clear that I would ever return, and Thai wanted to ensure that at least some of the lectures were preserved for future classes.
And so the day came, May 21, 2009, when we took out the components for the students to assemble and play with, to see how diffraction gratings worked in the rudimentary spectrometer. They were supposed to collect spectrometer data using their cameras or cell phones. The plan for using the software was a little vague; I hoped they would download the software at home or bring the data back the next day on a thumb drive so it could be processed on my laptop.
We opened up and distributed the batteries. Out went the LEDs. Out went the other components. And then came the surprise. Edmund Scientific had sent double dispersion gratings instead of linear dispersion gratings. I was stunned – I’d never seen such gratings before. They diffracted light in both the x and y directions. But I quickly recovered. “Good thing I made that software flexible,” I thought. “We can handle light no matter what orientation it diffracts in. Good job!” The students, at least in the front portion of the room, seemed very involved, they were having so much fun actually making instruments with their own hands.
Pictures are stills from a video made by Prof. Nguyen Thi Thai, VNUS-H.
