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March 21, 2002

Pitt researcher explores why some scientific concepts are so

difficult to grasp

Hot coffee won't stay hot for long in a Styrofoam cup, a middle school student once told Pitt psychology professor Michelene "Micki" Chi.

"The heat in the Styrofoam cup is gonna escape," the student said, "because a Styrofoam cup is not totally sealed because there's like…little holes in it."

A wrong, but revealing, explanation. Like Medieval scholars who envisioned heat as a substance they called "caloric," the student mistakenly viewed heat as a form of matter that can escape or be trapped — when, in fact, heat is an equilibrium-seeking process in which energy passes from hotter substances to cooler ones. Molecules are not hot or cold; it's their speed that generates temperature.

To Chi, the leaky-Styrofoam explanation exemplified students' misunderstandings of scientific concepts. Research by Chi and other educational psychologists has documented that certain science concepts are extremely hard for students in middle school and high school to learn.

But why some concepts, and not others?

And how can educators change their teaching to help students overcome na•ve, scientific misconceptions?

During a brown bag lecture at Pitt's Learning Research and Development Center, Chi talked about her 10-year search for answers to those questions.

Over the years, Chi said, teachers have suggested various explanations for students' hard-to-shake misconceptions of science: Scientific concepts are abstract by nature. Students lack prerequisite knowledge or logical reasoning ability. Science is just plain hard to understand.

But those explanations themselves don't hold up under scientific scrutiny, according to Chi.

She cited a 1994 study in which she and other researchers found that 57 percent of 8th graders examined could completely understand the human circulatory system after reading a passage about it, although all of the students began with incomplete understanding.

In contrast, an earlier study found that only 1.8 percent of high school biology students fully understood the arguably no-more-complicated process of diffusion (the gradual mixing of the molecules of two or more substances, as a result of random thermal motion) even after being exposed to the concept more than once.

Even the student who visualized hot molecules leaking through the holes of a Styrofoam cup was not guilty of illogical thinking, Chi noted, however fanciful his underlying misconception of heat flow may have been. He recognized heat transfer as a process in which heat flows from one location to another.

"More importantly, simply asserting that students misrepresent processes as concrete entities does not give us any guidance about how instruction can facilitate their learning of the correct conception," Chi said. "Thus, misconceiving of heat as hotness or hot molecules does not explain the fundamental flaw in [students'] explanation of heat transfer."

Chi's research suggests that students chronically misinterpret what she calls "emergent" processes as "causal" ones.

In the latter, a causal agent (something or somebody) takes action that results in a causal consequence (something happens).

Emergent processes are subtler, though not necessarily more complex. "The consequence of an emergent process is not caused by a single agent," Chi said. "It's caused by multiple agents doing their own things. But, if you sum those things up, you can see a pattern.

"Think of the stock market. At the end of the day, you can say that the market as a whole went up or down. You can even say that individual stocks went up or down in value. But those consequences are not the results of any single person's buying or selling."

One reason that students confuse emergent and causal processes, Chi said, is that emergent processes often involve a number of often-unrelated causal processes.

"The mechanism of flow of water downstream is a causal one and the mechanism of heat flow is an emergent one," Chi noted, "and yet at the macro level — water flowing downstream, and the feel of hot air flowing into a cool room — both are causal processes."

Chi and her colleagues are designing instructional texts and computer simulations aimed at helping students recognize emergent processes. "There are core features that we can identify for emergent processes, such as the unrelated actions of multiple agents at the micro level leading to a consequence at the macro level," Chi said.

"Part of the solution may lie with simply exposing students to the idea of emergent versus causal processes," she said. "Teachers might benefit students just by pointedly calling to their attention things such as heat being a process rather than a substance."

— Bruce Steele


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