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FCI Gain Limit?

September 12, 2012

What kinds of factors limit student conceptual gains in introductory physics?

Take-home message: Secondary trends observed in a study suggest that the average HS senior/beginning college student will face a limit to conceptual gains possible in standard lecture-based instruction of introductory physics. Very high conceptual gains among students in a lecture-based course are only attainable by students with the most developed scientific reasoning abilities (which is a small subset of the HS/beginning college student population).

As part of my PhD research at the University of Oklahoma, I investigated the interdependencies of

  • changes in everyday usage of technical terminology (in particular, the word “force”),
  • conceptual gains in first semester algebra-based physics classes and
  • scientific reasoning ability.

The working hypothesis was that those who demonstrated greater scientific reasoning abilities and had greater conceptual gains would stop their loose (and technically inaccurate) usage of “force” in colloquial usage. In short, I expected that students who demonstrated an aptitude for physics would not mix “force” with other terms (like energy, momentum, strength, etc.).

While the hypothesis was not fully supported, there were other trends revealed that dovetailed other work in Physics Education Research (PER) (see the work of Coletta and Phillips) and can serve as a source for further study. The scatterplot below is pretty loaded. While the axes suggest one trend, the color coding reveals something more subtle:

MLU stands for Mechanics Language Usage instrument (developed for the study). FCI refers to the instrument used to determine conceptual gains in 1st semester physics. “Developmental Stage” refers to performance on a reasoning ability test and is actually much more detailed than 3-point scale–it was reported in this way for simplicity.

The axes suggest the opposite of what was hypothesized: Namely, those with the greatest conceptual gains actually changed their loose usage of “force” the least. And it wasn’t because they had the usage correct to begin with . . . These students were simply more resistant to changing their language usage. I have to admit, the lack of delineation between a decrease and an increase in the amount of “mixing” (loose usage of “force”) was a bit disappointing. I was hoping for more dots above zero.

But look at the vertical dashed lines added to the graph. Notice that to the right of the green line (a gain of 0.65) there are no green dots. To the right of the blue line (a gain of 0.5), there are no blue dots. These are effectively conceptual limit lines based on performance on the reasoning ability test. The average HS/early college student scores nominally in the range of the blue to green category in scientific reasoning ability (an indirect measure of developmental stage). These are potentially gain limits. For additional information on “gain” as reported here, see this document by Richard Hake.

Full Disclosure:

  1. It’s important to note that the participants in this study were enrolled in a typical lecture-based physics class (3 hours lecture, 2 hours lab, 1 hour recitation) with only limited interactive engagement components. So one could argue the data suggest that this format of instruction (primarily lecture) imposes a limit on gains for the average student.
  2. I would be inattentive of me to neglect to mention the successes Modeling Instruction has had in this arena. Modelers report average gains in excess of .85 for students of similar demographics. The highly engaging environment of their classrooms make conceptual gains acheivable despite the varied levels of proficiency in scientific reasoning ability.
  3. Although this study involved 240 participants across two universities, these findings are exploratory– secondary to the intent of the original research question. Which means however convincing the arguments above may seem, further study designed to test that question really needs to be done.
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