Download Using a taxonomy of words in science teaching

20 Language and literacy in science education
BOX 2.4 A taxonomy of the words of science
Level 1: Naming words
1.1 Familiar objects, new names (synonyms).
1.2 New objects, new names.
1.3 Names of chemical elements.
1.4 Other nomenclature.
Level 2: Process words
2.1 Capable of ostensive definition, i.e. being shown.
2.2 Not capable of ostensive definition.
Level 3: Concept words
3.1 Derived from experience (sensory concepts).
3.2 With dual meanings, i.e. everyday and scientific: for example, 'work'.
3.3 Theoretical constructs (total abstractions, idealizations and postulated
entities).
Level 4: Mathematical 'words' and symbols
De Broglie's statement of wave/particle duality presents problems at an even higher
level of abstraction. It is impossible to conjure up even a vague mental image of a
particle being a wave at the same time.
This all indicates that it can be useful to divide the words of science into various
types or categories. Through doing this, science teachers can become more aware of the
language they use in classrooms. A classification or 'taxonomy' of the words of science
(first suggested in Wellington 1983) is shown in Box 2.4. Each category of words
acquires meaning in a different way, and it is this complexity that teachers of science
need to be aware of.
The first category can be called naming words. These are words that denote
identifiable, observable, real objects or entities: words like 'trachea', 'oesophagus',
'tibia', 'fibula', 'fulcrum', 'meniscus', 'vertebra', 'pollen', 'saliva', 'thorax', 'iris', 'larynx'
and 'stigma'. Many of these are simply synonyms for everyday words already familiar
to pupils, like 'windpipe', 'backbone' or 'spit'. Thus part of learning in science involves
giving familiar objects new names. At a slightly higher level, some learning in science
involves giving new names to unfamiliar objects, objects which pupils may never have
seen before - perhaps because they cannot be seen with a naked eye (such as a cell) or
because they belong to the world of school science laboratories: for example beaker,
conical flask, Bunsen burner, spatula, gauze and splint.
The second category of scientific words, at a new level of abstraction, can be called
process words. These are words that denote processes that happen in science: words like
'evaporation', 'distillation', 'condensation', 'photosynthesis', 'crystallization', 'fusion',
'vaporization', 'combustion' and 'evolution'. Clearly, some of these process words
acquire meaning for a pupil more easily
Looking at the language of science 21
than others. A teacher can point to a reaction on the front bench and say 'there,
that's combustion', or demonstrate red ink losing its colour and say 'that's
distillation'. Thus certain processes are in a sense visible, or at least 'showable'.
Their meaning can be learnt by ostensive definition (from the Latin ostendo, 'I
show'). Other processes belong to a higher level within this category. One cannot
point to something happening and say 'That's evolution'. Through education and
language development, 'evolution' may also become a concept (i.e. level 3.3).
The third, and largest, category of words in science are concept words. These are
words that denote concepts of various types: words like 'work', 'energy', 'power', 'fruit',
'salt', 'pressure', 'force', 'volume', 'temperature', 'heat'. This area of learning in science is
surely the one where most learning difficulties 1 are encountered, for concept words
denote ideas at gradually ascending levels of abstraction. The difficulty is magnified
because these words cannot l be understood in isolation. They are part of a network of
other words, all related together, often in a 'vertical' structure, i.e. the understanding of
one word (such as power) depends on prior understandings of other words (such as
work and energy). Without prior understandings, the structure collapses.
We should also note that many words can jtfart .as a name but, through language
development in science, gradually be used as a concept. For example, fuel may be a
name for petrol or paraffin, but gradually it acquires a general, conceptual meaning,
such as 'a flammable material yielding energy'; III similarly with the terms 'salt' and
'gas'.
At the lowest level, certain concepts are directly derived from experience. Like
certain processes, they can be defined ostensively by pointing out examples
where the concept pertains. Colour concepts, such as 'red', are almost certainly
learnt in this way. These can be neatly termed sensory concepts. The next category
contains words that have both a scientific and (perhaps unfortunately) an
everyday meaning: examples include 'work', 'energy', 'power', 'fruit' and 'salt'.
The existence of the two meanings causes pupils difficulties and confusion. It also
explains the seemingly strange yet often perceptive conceptions (alternative
frameworks) that pupils possess of 'heat', 'plant nutrition', 'pressure', 'energy',
'work' and so on. The same word is being used to denote two different ideas. In
these cases the invention of totally new words (such as 'anode' and 'cathode'
coined by Faraday) might have made life easier for generations of school science
pupils. Finally, concept words belonging to a third level are used to denote what
we will call theoretical constructs: words like 'element', 'mixture', 'compound',
'atom', 'electron', 'valency', 'mole', 'mass', 'frictionless body', 'smooth surface',
'field'. Some of these theoretical constructs, such as atom and electron, people may
prefer to call unobservable entities because in a sense they exist. Others are simply
idealizations, or total abstractions, which cannot possibly exist, such as point
masses or frictionless bodies, except in the language of mathematics.
The language of mathematics, its 'words' and symbols, can be placed at the
fourth and highest level of abstraction in a hierarchy of scientific words. The
mathematical language used in advanced physics is neither derived from,
nor directly applicable to, experience. Its meaning is so detached as to become
almost independent of the physical world.
22 Language and literacy in science education
Using a taxonomy of words in science teaching
This hierarchy or classification is all very well, you might say, but of what possible
use can it be to the science teacher? What implications does it have? There are four
areas where it might be applied:
Beware of meaning at the higher levels
Different scientific words mean in different ways. The word 'iris' means simply by
labelling or pointing out an observable entity; similarly with many other words in
level 1 of the taxonomy. They have a direct, concrete referent. Some entities, such
as cells, require microscopes for pupils to acquire a meaning. But the meaning of
words in higher levels is not as clear. At best they denote, or refer to, some mental
image or abstract idea.
Words in the highest level of the taxonomy, such as 'electron', can only have
meaningJn_a,theoretical context. The meaning of 'electron' somehow belongs to a
theoretical world of nuclei, atoms, electric fields, shells and orbits - an imaginary,
almost make-believe world to pupils starting science. Yet 'electron' can acquire
meaning, just as the words in a far-fetched fairy tale do.
Highly abstract ideas have no visual, concrete referent. 'Talking them into
existence' takes a lot longer and requires more practice in using the word. The
problem of meaning (or rather lack of it) at these higher levels of abstraction must
be a major cause of failure in science education.
Are pupils 'ready'?
The lack of meaning for many pupils of scientific terms in level 3 of the taxonomy
particularly may explain why many pupils fail to make sense of science. Perhaps
they meet these words too soon - indeed, the hierarchy in the taxonomy could be
closely related to Piagetian stages of development. Is it possible, for example, for a
pupil to acquire any meaning for a term denoting a theoretical construct before he
or she has reached the formal- operational stage? More positively, can science
teaching help to achieve the required readiness and development?
Formal-operational or not, pupils won't have a chance of understanding words
high in the taxonomy unless careful attention, and time, is devoted to language.
Language development
A conscious awareness of gradually ascending development of meaning can often
be useful to the science teacher in classroom teaching and lesson preparation. By
developing word meanings for pupils - for example, from a