Chemistry Reference
In-Depth Information
discontinuous: often the preconceptions have to be given up and radical res-
tructuring needs to take place. Conceptual growth and conceptual change interact
just like assimilation and accommodation.
Preconceptions
. At the beginning of chemistry learning the students have
cognitive structures, which, according to the constructivist idea, were built on the
basis of their lifelong experience. These preconceptions are deep rooted, for
example, the assumption of the destruction concept for combustion processes (see
Chap. 1). There also exist spontaneous conceptions, which arise during the class-
room discussion: they are not deep rooted and easier to correct.
For lesson planning, attention should be paid to those preconceptions that are
deeply rooted in the student's cognitive structure: for example, concerning the
combustion process, the law of conservation of mass, properties of gases, and the
structure of matter (see Chap. 1). The student conceptions may be discussed in class
before the scientific idea can be taught with convincing experiments and models.
The so-called common-sense explanations or colloquial explanations belong to the
deep-rooted preconceptions: often they are “socially accepted misconceptions”
[
26
]. One example is that the sun is “going from the East around the earth to the
West during one day” - instead of pointing out that the sun is fixed and the earth is
revolving around the sun.
Attitude and interest
. They should be taken into account for the lesson goals and
lesson planning too. If the learner has a negative attitude towards chemistry or a
certain topic in chemistry, it is more difficult to reach set goals in this subject than it
is in others, towards which the learner has a positive attitude. If there is a positive
attitude towards music or arts, students are highly motivated to follow those
lessons.
With pictures drawn by Swiss students in 1983, Heilbronner [
28
] could show
that their attitude towards chemistry and chemistry lessons was absolutely negative:
“the vast majority of students felt themselves and the environment to be threatened
by chemistry.” Around 40% of the pictures showed a destroyed environment, 15%
the direct threat to the individual by chemistry and 10% opposed animal testing.
Barke and Hilbing [
29
] picked up on this exercise “draw your picture of chemistry”
and repeated the study in 1998: the proportion of negative pictures, which was
around 65% in Heilbronner'
S
study, decreased to 40% (see Chap. 8).
M
uller-Harbich et al. [
30
] analyzed secondary school students' attitudes. They
found the attitudes to be neutral or negative, without a significant gender-related
difference. The place of residence, however, had a significant impact on the
attitude: students who live in an area full of industry show a more negative attitude
than students who do not live close to industrial locations. When students have a
positive attitude towards a subject, they are more likely to develop an interest in
contents of this subject. If specific student interests are known, it is helpful to take
these interests into account for planning lessons.
Gr
€
aber [
31
] analyzed students' interests and could prove that around half of all
participating students are interested in chemistry lessons: “this is remarkable
insofar as interest rises with the beginning of chemistry lessons in grade 8 and
rises again in grade 10, after a 'hole' in grade 9.” He also found differences between
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