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Most teachers of chemistry agree that the general chemistry laboratory plays an essential role in teaching our experimental science. There is not so much agreement, however, on what role the laboratory should play. Quite typically, the laboratory follows the lecture with the intention of reinforcing the concepts that have already been covered in the classroom. There are cases where the topics of the classroom teaching and the laboratory work have drifted away from each other, and the primary role of the laboratory becomes teaching chemical techniques. In the opposite approach, the discovery approach, the laboratory drives the course. Concepts are initiated by student experimentation, and then these concepts are expanded in the classroom.
Discovery learning was the topic for the Tenth Annual Worcester Polytechnic
Institute Conference on Chemical Education held on October 19, 1996, for high school, college, and university teachers of chemistry. The speakers for this conference were Richard S. Herrick, Department of Chemistry, College of the Holy Cross, and Nicholas K. Kildahl,
Department of Chemistry, Worcester Polytechnic Institute.
Herrick's presentation was entitled "Reflections
on Discovering Chemistry at Holy Cross". He described
a mature discovery laboratory program that was
initiated in 1989 and involved all faculty in the
department. Building renovations had been performed to
provide space especially suitable for discovery learning,
with laboratory, discussion room, and instrument room
directly adjacent to one another or readily accessible.
The major instruments (atomic absorption, UV-visible,
Fourier transform infrared, and gas
chromatographymass spectroscopy) were selected to produce data quickly,
making it practical for individual students to measure different data
points and pool their data to construct meaningful graphs.
In a typical learning period, a question is posed in the discussion room
and the students as a group design a plan to arrive at
an answer to the question. The students then do
experiments in the laboratory to develop hypotheses and
test them. After this is completed, they return to the
discussion room to draw conclusions. The experiments are
carefully designed so that at the beginning of the
exercise, it is not clear to the students what the results of the
experiment will be or where the discussion will lead.
The experiments are not open-ended but rather are
intended to guide students through a laboratory exercise that
will promote discussion and allow the reaching of
conclusions.
Herrick described a simple experiment involving
the masses and densities of pennies. It was notable that
thorough discussion of even such an elementary exercise
developed many concepts: uncertainties, intensive and
extensive properties, scientific method, and graphing
linear equations. Benefits of the discovery laboratory
approach include fostering learning in and out of the
classroom, providing a less threatening environment for
students with different backgrounds, connecting
lectures and laboratories, and teaching critical thinking.
Problems with this approach include greater use of
faculty time, scheduling problems because time blocks
are longer, and lack of commercial resources.
Herrick concluded by giving his view of the
components necessary for a new discovery laboratory
program: (i) development is necessary to adapt to a specific
site, (ii) departmental consensus is required, (ii)
whole-scale change works better than piecemeal change, and
(iv) modern instrumentation is highly desirable.
The title of Kildahl's presentation was
"Discovery Learning: Fact or Fantasy?" He expanded on the
discovery approach as being suitable to the laboratory
alone, the classroom alone, or linking laboratory and
classroom. For example, in the classroom students can be
presented with data and then participate in a guided
discussion to find patterns in the data and generalize concepts
from the patterns. As a simple example, pressurevolume
or volumetemperature data can be presented with the
aim of deducing Boyle's or Charles's law. Key aspects of
discovery learning are students build their own
understanding, classroom learning becomes interactive, the
actual process of science is approximated, students feel
the thrill of discovery, and more of the effort of learning
is placed on the shoulders of the students.
In the panel discussion that followed, there was
a clear interest in using this kind of learning in high
school and college chemistry classes, but there was also
concern about the effort and expense involved.
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