When students come to Professor Geiser’s office, he won’t quit,” says Carsten Neilsen, a graduate student who works with Geiser. “When they’re done asking their questions, he’s still asking them questions. He wants to take them somewhere else.”

Where he wants to take them is into a deeper knowledge of the world around them through the physics of chemistry. They discover, for example, that the simple act of pulling a ring off the surface of a liquid can give you enough information to calculate the diameter of a molecule in the liquid. But Geiser says he also wants to take students to a place where they can “be the ones doing the thinking” and ultimately “think like a scientist instead of a student.”

“Instead of doing it all for you, he’d ask you the right question,” recalls student Steve Pieroni, who took physical chemistry with Geiser. When Pieroni asked for help with a difficult calculation, Geiser said, “Remember those two little rules about how you can multiply by one or add zero? Think about it!”

It’s in Geiser’s labs where students really get a chance to start thinking like scientists. Three years ago one of his students received an “A” on a 20-page lab report—and then failed the portion of a test on that procedure. “I realized that the way the labs were set up, the students had very specific instructions telling them how to do every step of the manipulation and every step of the calculations. ‘You plug in this number here and there.’ And that’s how certain students could write 15 pages on the topic and learn ZERO!”

So Geiser abandoned the conventional “cookbook” approach to lab work. Instead, he adopted the more open-ended approach in use at a growing number of schools, including Brown, where Geiser taught as a graduate student. Pieroni describes it this way: “He gives you the theory, all the equations you need, and what piece of equipment to use. Then you have to think about what values you want to measure and what correlations you want to make—and you design your own experiment.” The students have two weeks in which to perform their experiment; more than once, if necessary. A 20-page report at the end gives them practice writing in the format used by professional scientists.

Geiser’s questions extend the students’ learning further and reveal the level of their thinking. After they perform a classic combustion calorimetry experiment measuring the heat for fuels inside a stainless steel vessel, he might ask, “Why do we charge the vessel with 30 atmospheres of oxygen when the reaction only requires six atmospheres?”

“Because you told me to!” is the likely reply from a student who’s used to following recipes. But students who are beginning to think like scientists will try to answer the question on a molecular level. Even a wrong answer can provide a good starting point for a discussion on why extra molecules of oxygen are needed to ensure that “molecules will collide and chemistry will happen.”

Now the students sometimes surprise Geiser with their ability to find new implications in the lab work, and they’re better prepared to perform the original research required for their senior project. But there’s another compelling reason for teaching this way. “It’s more fun to talk about science with somebody,” Geiser notes with a smile, “than it is to talk about recipes.”

—Virginia Stuart,
College of Engineering and
Physical Sciences