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The article "Assessment of Knowledge Acquired in
an Organic Course", recently published in this
Journal (1996, 73, 231), constitutes a representative example of how
easy it is to obtain erroneous conclusions in this class of studies.
The authors posed to 108 students four options to
explain why glycerol is a polar compound, namely:
- Alkane is classified as nonpolar and glycerol as a
polar compound because all alkanes are nonpolar.
- The hydroxyl functional group is polar.
- The differences in electronegativity of the
different bonds can be analyzed.
- Based on its polar bonds, glycerol is a polar
compound, which distinguishes it from alkanes.
After analyzing the responses they conclude that
83% of students "...could give a description of the problem,
analyze it... . ...we consider these results to be acceptable
in terms of knowledge demonstrated by these
students... ."
This conclusion seems to me unacceptable. I
imagine 108 students thinking which of the four few consistent
options will be considered correct by their teachers, the
83% deciding for 3 (because analyzing something is always
appropriate) or 4 (basing on something is also convenient).
Alternatively, the 83% of the students decide according to
what they have learned from their teachers.
Indeed, the authors consider that the best
alternative to explain the fact that glycerol is a polar compound is
option 3. Probably a printer's devil replaced atoms by
bonds but, as written, a normal student would never
select this option. The second-best alternative, also
according to the authors, is option 4. Maybe they ignore that the polarity
of the bonds is not a condition sufficient to make a
molecule polar.
Consequently, a plausible interpretation of the
results of the study is that 83% of the students followed the
course, in this case unfortunately, with sufficient attention. However, 18 students (those moving against preoccupation
with their teachers by having selected option 2) showed
resistance to accepting erroneous concepts and selected
the unique statement as correct.
Interpretations apart, the main conclusion I have
obtained after reading this article is: also in a Facultad
de Ciencias Agropecuarias, chemistry courses should be
conducted by a Department of Chemistry instead of - as
recognized in the article - by the Applied Biology Department.
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