Models
When ninth grade students
were asked what a model is, there first response is "A person who shows
off clothes and walks down a runway." When the students were focused
on to the other kinds of models like those used in science, the responses
matched a lot of what they had learned in their biology class. Jack
said, "Models are things that people make that resemble living things.
They are miniature versions of real life things." Cynthia responded,
" Models can be peoples or things used to either make a point about how
something works or looks." Both Jack and Cynthia, along with Jill,
said that the more details and the more specific the details of the model,
the better the model is.
These responses are
consistent with what Driver and her associates discovered in their research.
"Models are seen to map on to events in the world in an unproblematic way,
a perspective described by Carey et al. (1989) as a correspondence
view of theories" (Young People's... 139). Students only think of
models as those represented to show things that scientists know exist.
When asked for examples the three students mentioned models of cells, the
human body, and the water cycle, none of the students mentioned the idea
of the model of the atom or the Kinetic Molecular Theory which is also
a model. These models are not miniature (or expanded) views of things
we can see like the cell or the human body, but they are scientists "best
guesses" as to what an atom looks like or how gases behave. Students
have this idea that an model in science is completely accurate, which is
incorrect. Many models are just theories scientists are using to
explain phenomena that can be observed. Models are not absolute but
many students, because of other exposure, do not understand models and
their uses in science.
Atoms
"Very small organisms,"
"smallest things that make up everything," "smallest units of matter" --
these were the responses given by Jack, Jill, and Cynthia when they were
asked "What are atoms?". These responses are again consistent the
research. "Some children spontaneously generate the idea that materials
are composed of 'small bits' or 'particles'" (Making Sense... 92).
The students have the idea that there are these tiny things but as is noticeable
from the first response, the students are unclear on what the tiny things
are made of, their properties, and what they look like. The students
know the particles are small but they have no real appreciation for how
small (Making Sense... 96). Jack mentioned the term microscope
when he was talking about atoms which for him is small but not small enough.
An atom cannot be seen with a typical microscope.
Not only in the size
of the atom a problematic source for students but also the properties of
the atom are as well. "Pupils often regard 'atoms' as 'small bits
of solid' (or as "small drops of liquid') that are static, non-uniform,
and without cohesive force (Making Sense.. 92). Students do
not understand that atoms are mostly empty space and that the electrons
are moving around constantly inside of the atom. It is a concept
that is rarely presented to them and not one they will likely come to on
their own. When Jack, Jill, and Cynthia were asked what an atom looks
like the responses included "a circle," "a ball," and "a big rock " (size
characterization was interesting). When asked how they knew this,
Jack said "from science class", Jill responded "It's in books," and Cynthia
said, "a diagram." Though the general addition of the orbitals
and probability distributions gives a spherical space, the idea that an
atoms is made up of empty space seems to escape them.
Light
Light is another difficult
concept for students. The idea that light is traveling energy is
not clear to students at all. When asked "What is light?" Jack said
that light is a "reflection of bright colors." Jill responded that "it
is a reflection of the sun and electricity is made through energy in connected
circuits." Cynthia said first that "light is light." After
a moment she said that light is "a bright source of energy. The world's
light comes from the sun but a room has light bulbs." The idea that
energy is involved in clear in both Jill and Cynthia's
responses but they are not really sure how. They also have the ideas
of how we see light, reflection, involved in their responses but it is
not clear that they understand that light is just energy which travels
and whose frequencies our eyes can detect.
Research has shown
that students responses about what light is is very subjective to the culture.
Light could mean not dark or the physical thing that light comes from ("Turn
on the light"). There is no clear trend for students ideas on light
except for that students do not have a clear scientific idea of what light
is. (Making Sense.. 128-29). When asked about how a lamp works
"Anderson and Smith found that more than 75% of the sample of 227 did not
choose the scientifically correct answer" (Making Sense... 129).
Students do not understand that light has energy or that different colors
of light have different wavelengths (and thus different energies).
Students ideas on light are very pieced and need help in clarifying them.
Light Producing
Atoms (in the form of Na/Ne Lights)
The final question
asked of Jack, Jill and Cynthia was "We have lights we call neon lights
or sodium lights. Why do we give these lights the names we do?"
They were also asked then how they worked. This question was designed
to see if students had an knowledge of Atomic Spectra or the idea that
atoms can produce light. Jack, Jill, and Cynthia did not seem to
have any idea about the workings of these lights. All three of them
seemed to guess that we called them sodium and neon lamps because that
is what they are made of. However, none of them even had a guess
how they worked. Jill provided the closest idea when she said "because
of what they use to make light." The idea that the sodium and neon
are involved in making the light is there but the idea that sodium and
neon can actually produce light is not. This concept, that atoms
can give off light, seems to be am almost brand new idea for the students.
Sources:
Driver, et. al. Making Sense of Secondary
Science, Research into children's ideas. London: RoutledgeFalmer, 1994.
Driver, et. al. Young Peoples Images
of Science. Philadelphia: Open University Press, 1996.
Interviews with students at Champaign
Centennial High School.
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