Chemistry Reference
In-Depth Information
and take students away from their new acquired scientific ideas. Objective consumer
guidance can take up positive aspects and support the new conceptions. In this sense,
Becker subjects consumer questions in a TV show to a scientific reflection [
30
].
Problems and Exercises
P1.1. Some students' misconceptions are also conceptions from scientists of past
centuries. Give three examples and show parallels between historic
conceptions and preconceptions of students today. Explain the scientific
bases of the given examples.
P1.2. In explanations of natural processes or laboratory phenomena, children often
reason in a “magical-animistic” way. Name three examples for such
reasoning. Explain the scientific bases and suggest corrected explanations
that are suitable for children.
P1.3. Chemical compounds are often described by sentences like “they contain the
elements” or they “consist of elements” (“water consists of hydrogen and
oxygen”). Which problems hide behind such comments? Suggest expressions
that are correct from your point of view. Consider Dalton's atomic model and
propose correct expressions from that point of view as well.
P1.4. Concerning the structure of matter terms like “continuum” and
“discontinuum” on one hand, “preformed and nonpreformed particles” or
the “horror vacui” on the other hand are used in chemical education. Explain
these discussions. Which teaching ideas, which experiments and models do
you suggest for teaching these issues?
P1.5. Experiments are convincing instruments to make students realize their
misconceptions and to motivate them to reduce or to change their
misconceptions in favor of scientific ideas. Describe three examples of
misconceptions and the experimental procedure to outline the reduction of
these mistakes.
Experiments
E1.1.
Torricelli's Experiment on the Existence of the Vacuum
Problem: Air pressure is neither palpable nor concrete for scientists of past
centuries or today's students, even when the weather forecast gives the
current air pressure in millibar or hectopascal every day. Torricelli's his-
toric experiment is a good opportunity to illustrate the balance of a 20-km-
air column and a 760-mm-mercury column. On the basis of this experiment
students are able to understand a mercury barometer, and so the air pressure.
