Chemistry Reference
In-Depth Information
Nearly every student has to undergo a big conceptual change concerning the
interpretation of burning coal, candles, or alcohol. The teacher can talk and talk -
they will still not convince young students to overcome their destruction theory.
The only way to achieve this is by interpreting convincing experiments and
structural models (see Sect.
1.2
). For example, the conservation of mass should
be shown by burning pieces of coal in a closed flask and weighing before and
afterwards (see E1.9). Structural models of carbon and oxygen before the reaction
and carbon dioxide afterwards show that atoms are only rearranged, no atom is
missing, no atom is added - so the mass has to be the same. Over weeks and months
the students may start to change their destruction concept in favor of the conserva-
tion of mass, however, some students will not change their old conviction at all.
Concept Cartoons
. For diagnosis and challenge of misconceptions, Temechegn
and Sileshi [
19
] developed concept cartoons (see an example in Fig.
1.10
).
Concerning the conservation of mass they asked: “What is the mass of the solution
when 1 kg of salt is dissolved in 20 kg of water?” [
19
]. The correct answer “21 kg”
is given by one of the students in the cartoon (see Fig.
1.10
), but three other answers
are also given, especially the answer “20 kg” for those who are thinking: “the salt is
gone and the water tastes salty - but weighs 20 kg as before.” Students can discuss
all four answers and the teacher may diagnose the different kinds of misconceptions
in their class. Since the question is “what do you think” even more than four
answers can appear. After some hours of instruction with experiments and struc-
tural models, students may have a second look at that concept cartoon to compare
the just learnt scientific answer with the other misconceptions - they can even tell
what is wrong with those alternatives. Through discussions of concept cartoons
both teaching processes are possible: diagnosis
and
challenge of misconceptions.
For other topics, some more cartoons are shown at the end of this chapter.
Learning Doctor
. Taber developed the picture of a “Learning Doctor” as a means
of discovering individual misconceptions and a suitably related science lesson regard-
ing conceptual growth or conceptual change [
20
]. “Auseful metaphor here might be to
see part of the role of a teacher as being a learning doctor (a) diagnose the particular
cause of the failure-to-learn; and (b) use this information to prescribe appropriate
action, designed to bring about the desired learning
...
Two aspects of the teacher-as-
learning-doctor comparison may be useful. Firstly, just like a medical doctor, the
learning doctor should use diagnostic tests as tools to guide action. Secondly, just like
medical doctors, teachers are 'professionals' in the genuine sense of the term. Like
medical doctors, learning doctors are in practice (the 'clinic' is the classroom or
teaching laboratory). Just as medical doctors find that many patients are not textbook
cases and do not respond to treatment in the way the topics suggest, many learners
have idiosyncrasies that require individual treatment” [
20
].
Including misconceptions into lectures
. In a project in progress, Barke and
Oetken intend to diagnose preconcepts and school-made misconceptions [
21
], but
in addition they will integrate them into lectures to develop sustainable understand-
ing of chemistry. For 20-30 years educators have been observing nearly the same
misconceptions of students, and that corresponding lectures at school are not changing
much. Hence, being convinced that preconcepts and school-made misconceptions
