Teacher-training students' conception of matter and substances, some results from 31 interviews.
Bjørn Håland, University of Stavanger, Norway
Background, aims and framework
Introductory chemistry seems to be a worldwide problem that researchers have wrestled with
for many years (e.g. Andersson, 1990; de Vos & Verdonk, 1985; Johnson, 2000b; Nakhleh,
1992). The particulate view of matter was early singled out as a key problem (e.g. Nakhleh,
1994; Nussbaum & Novick, 1981), in addition to chemical reactions (e.g. Andersson, 1990;
de Vos & Verdonk, 1985; Johnson, 2000b), phase changes (e.g. Andersson, 1990; Stavy,
1990; Stavy & Stachel, 1985) and the gaseous state (e.g. Johnson, 1998a; Stavy, 1988).
In the last years two, perhaps even more fundamental, concepts have added to the list: the
concept of matter (Nakhleh et al., 2005; Stavy, 1991) and the concept of a substance
(Johnson, 1996, 2005). An interesting aspect in this connection is Johnson's (1998a; 2002)
findings that some understanding of the particulate view of matter seems necessary to
understand all these key concepts and vice versa
A key concept within human constructivism (Ausubel et al., 1978; Novak, 1993) is
meaningful learning. New concepts always have to be tied to existing concepts in the learners'
cognitive structure. As a teacher with this view of learning and teaching, one would claim that
it is important to know something about the students' prior ideas. Only then one can pick out
the "relevant anchoring concepts available in the learner's cognitive structure" (Ausubel et
al., 1978, p. 358) and make the teaching meaningful.
This investigation brings forward some knowledge about what Norwegian teacher-training
students think about matter and substances and to what extent they use a particulate view of
matter when they try to explain phenomena. The research question therefore was: To what
extent do teacher training students' views of matter and substances differ from the scientific
view, and is it possible to find any common relevant anchoring concepts for introductory
chemistry education.
The concepts of matter and substances are used from day one in chemistry teaching. If one, as
a teacher, wrongly assumes that the students understand and use these key concepts the same
way as oneself, there is most probably a crucial communication problem (Johnson & Gott,
1996). For students that use these concepts differently, major parts of the chemistry teaching
must be a mystery, and they are left with only one option: rote learning.
Methods and samples
Science is not a compulsory subject in Norwegian teacher education. At University of
Stavanger the teacher-training students can optionally choose to include 30 + 30 credits
(ECTS) science as part of their education. Introductory chemistry (10 ECTS), is one module
within this science education. It is reasonably to assume that it is the students who are more
interested (and able) in science, that choose these courses.
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31 students were interviewed before they started the introductory chemistry course. The
interviews were semi structured and linked to practical tasks. All interviews were tape
recorded and some photos were taken.
The students were initially introduced to a selection of (29) different objects, and asked to sort
them as they wished. They were asked if they could see anything in common to all these
objects and comment on that. Later 8 single-substance objects were picked out and they were
asked if they could see anything in common to these and comment on that.
The students were then asked to explain the results and what had happened to the substances
in 5 practical demonstrations: evaporation of water, the missing stearin of half burnt candles,
formation of dew (water), melting of stearin and dissolving of coarse salt in a glass of water.
The interviewer consistently tried to avoid any expression that could hint what had happened
to the material.
The interview was finished with a discussion of the meaning of some (Norwegian) words:
"stoff" (stuff / matter) and "materiale" (materials), the borderline between "stoff" (stuff /
matter) and not "stoff" and the difference between "enkeltstoff (reint stoff)" (a substance) and
"stoffblanding" (a mixture).
The interesting parts of the interviews were partly transcribed. The results were coded, sorted
and analyzed.
Results, conclusions and implications
As space is restricted only three main aspects will be discussed: the two concepts matter and
substance and the particulate view of matter.
In classical science, there is a strict borderline between what is material and what is not
material (Chi et al., 1994). This investigation revealed several non scientific views of matter.
A few examples: Only a few students could see anything in common to all the objects to be
sorted. Statements like “different substances” or “built from atoms” were mentioned. Some
claimed that the missing stearin had become energy, light or heat, and for some it had just
disappeared. Others had no explanation for the dew outside the glass of water with ice cubes.
About 1/3 of the students did not conserve mass (weight) during the dissolving process and /
or melting process.
When asked directly about the borderline between matter ("stoff") and nonmatter
("ikkestoff"), 6 students would (commonly) only think of solids as matter / stuff ("stoff").
Another 4 would include the liquids but not the gases. 3 would not include natural or living
things among matter / stuff. Totally 21/31 students had one to several views on matter
("stoff") that did not correspond to the scientific view. It is interesting to notice that these
findings correspond well with Stavy's (1991) results for children grade 1-7.
In Norwegian the same word, stuff ("stoff"), is used both for the general term matter and for
substances. The idea of single substances, with its own identity and its own properties, is,
however, crucial for the understanding of chemistry (Johnson, 2000a). It is especially
important in connection with reactions.
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Although all students seem to recognize, use, buy and sell different substances, and are certain
they will remain unchanged if treated properly, most students seem to have a rather vague
notion of what a substance really is. When asked if they could see anything in common for the
8 single-substance objects, only one eventually recognized that they all were pure substances.
When asked directly about the expressions: a (pure) substance (“enkeltstoff / reine stoff”) and
mixtures (“stoffblandinger”), 13/31 expressed views that was scientifically (more or less)
correct. But when it came to evaporation, burning of candles and formation of dew, only 4 of
them gave explanations that show that they had reasonably good notions of substances. 16/31
thought that a single (pure) substance was one that contained only one element (“et
grunnstoff”). Their different notions agree well with Johnson's (2000a) work that shows that
"children do not 'naturally' have a concept of substance identity …".
This investigation had no task or questions that directly probed the students' understanding
and use of the particulate view of matter. Instead it was noticed how the students spontaneous
used these ideas during the interview. None of the students gave explanations that revealed
anything near a complete (basic) particulate view of matter. As many as 25/31 students,
however, sporadically mentioned some sort of particle (molecules, atoms, small piece,
particles), in a relevant way, one time or more in their explanations. It was most often
mentioned in connection with the solution of salt (21/31) and evaporation of water (10/31).
Only 4 students used some sort of particles relatively consistently across more tasks (4-8
times). This agrees well with Johnson's (1998b) and Nakhleh's et al. (2005) observations that
students only seldom uses particles spontaneously when they talk about substances.
Summing up over all the three main aspects discussed, 28/31 students either had some kind of
view of matter and / or substances deviating from the scientific one or they used ideas about
particles only sporadic. In other words, these basic and fundamental concepts in chemistry
seem to be rather poorly understood among our students. As our students most probably are
among those who are more interested and able in science, this probably also holds true for all
Norwegian teacher-training students. Assuming that these concepts are well understood must
generate many problems. For many, their only option must be rot learning (Ausubel et al.,
1978)
This investigation has uncovered a wide range of non scientific ideas about matter, substances
and the use of the basic particulate view of matter. These key concepts therefore clearly need
to be addressed as part of introductory courses in chemistry. Common and relevant anchoring
concepts, however, seem to be rather limited. As all students recognized solid substances as
matter, this could be used as one common starting point. By consolidating and expanding the
concept of substances the concept of matter can also gradually be expanded. As some
understanding of the particulate view of matter seem necessary to understand these key
concepts (Johnson, 1998a, 2002), the particulate view of matter must be taught
simultaneously. As many students spontaneously introduced some sort of particles in their
explanation of the dissolving of solid matter (salt) in water, this might be used as a starting
point.
These deviating ideas about matter, substances and the particulate view of matter must also
generate problems in part of the biology and ecology education (e.g. physiology, circulation
of nutrients etc.).
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