Chemistry Reference
In-Depth Information
schools, this was not the case: those kids have nearly no technical toys, boys and
girls have only few chances to develop spatial ability compared to kids of rich
parents of private schools.
Sopandi [
20
] developed for grade 9-12 students a test of chemistry understanding
with tasks concerning the structure of matter. The participants should draw their
mental models regarding the arrangements of particles before and after well-known
chemical reactions, particles in mineral water, or in acidic and basic solutions.
Besides this questionnaire, also the evaluated space test [
19
] was conducted in the
same classes and all data have been correlated: the correlation coefficients show high
correlation, good chemistry understanding correlates with good spatial ability,
spatial ability may be a prerequisite of chemistry understanding [
20
].
One last aspect of spatial ability will follow. Most curricula in science of grade
5 and 6 want the introduction of the particle model of matter: water particles in ice
crystals, in water drops, or in vapor clouds, ethanol particles in ethanol, water, and
ethanol particles in an aqueous solution. Schwoeppe [
21
] developed a space test
concerning the understanding of those model drawings and stated big differences in
spatial ability. Because the factor Space is just developing during the ages from
10 to 12, the training of this ability seems very important. One way for the training
may be building real models concerning the 3D-arrangement of particles on the base
of the simple particle model of matter, and by deriving those well-known 2D-model
drawings from real 3D-models: they are like many other models very important
media in chemistry education.
Prior knowledge
. The learners not only bring skills and ideas from their envi-
ronment into class (see Chap. 1) but they also experience many scientific topics in
nonfiction topics, children's magazines, or television shows. Teachers should be
familiar with these media, to be able to respond adequately, or even to incorporate
these media with chemistry lessons
Generally, students start science education with preconcepts or alternative ideas
about substances and their changes (see Chap. 1). Asking for example, “what is the
mass of the solution when 1 kg of salt is dissolved in 20 kg of water” [
22
], students
like to answer: “the salt is gone and the water is now salty, but has the mass of 20 kg
as before” (see Fig.
4.6
).
They do not speak about 21 kg of the
solution
, about reclaiming the salt if the
water were to be separated by evaporation: students do not have the idea of
conservation of mass. So the teacher has to take preconceptions from students
and to invoke a conceptual change to the law of conservation of mass.
Concept cartoons
. Those cartoons (see Fig.
4.6
) are good media to open the
discussion about students' different explanations. Temechegn and Sileshi [
22
]
designed concept cartoons for many chemistry topics and lectures. They stated:
“Concept cartoons are cartoon-style drawings that put forward alternative conceptions
about the science involved. By offering new ways of looking at the situation, they
make it problematic and provide a stimulus for developing ideas further. Concept
cartoons provoke discussion and stimulate scientific thinking. A typical concept
cartoon has the following features: visual representation of scientific ideas, minimal
text-in dialogue form, and alternative conceptions in equal status.
