Pedagogia

Chemistry Teaching—Science or Alchemy?

1996 Brasted Lecture

A. H. Johnstone

Department of Chemistry, Glasgow University, Glasgow G12 8QQ, Scotland

Introduction: Is Chem-Ed Research?

Many of us who work in universities have two main

roles: as researcher and as teacher. The balance between

these varies from one institution to the other, and the approach

to these roles can be very different. Some people see

teaching as a chore which gets

in the way of research, while

others view their teaching as

an exciting, creative, but often

frustrating pursuit. Journals

such as this regularly carry articles

describing some frontier

of chemical research along

with articles about teaching

innovation. Where the two

types of communication differ

is in their overt theoretical

stance. The research papers are copiously referenced to

theories, held beliefs, hypotheses, and objective measurement

and seek to build on and extend what has been done

before. The teaching papers, on the other hand, are full of

assertions, homespun wisdom, and ingenuity, and lack measurement.

I am suggesting that the development of good teaching

and the pursuit of research have (or should have) essentially

the same structure. We need some discipline in our

work to give it a clear focus, to be efficient in time and effort,

and to have a direction that is more often right than

wrong. We also need transferable outcomes that all can

share, to prevent the constant reinvention of fire.

The bulk of this paper is an attempt to do the gathering

together of things we have all been aware of, perhaps

intuitively, and to provide a working model for new research

and development in chemical education. It is an attempt to

systematize what is known into a usable form, which might

save us from confusing our enthusiasms for those of our students

and which will help us to go with the learning process

rather than across it or even against it!

The model draws upon the work of psychologists, educationists,

artificial intelligence workers, and dealers in

common sense.

Constructing a Model of Learning

In common with all living things, we are victims of our

environment, informed by our senses and reactions. However,

we have mechanisms by which we reduce the torrent

of sensory stimuli to manageable proportions, attending to

what seems to be important, interesting, or sensational. In

other words, we have a filtration system that enables us to

ignore a large part of sensory information and focus upon

what we consider to matter. To try to attend to everything

would be an impossibility leading to confusion and breakdown.

We then have to ask how the filter works. It must be

driven by what we already know and understand. Our previous

knowledge, biases, prejudices, preferences, likes and

dislikes, and beliefs must all play a part. How else would

we anticipate and recognize the familiar or be caught out

by a surprise?

Although in any one country or culture much of this

will be held in common, each individual will have a unique

set of held knowledge and beliefs that mark us out as separate

people and personalities.

Not only do we sense selectively, we also add, from experience,

to our sensory information

and “fill out” an otherwise

incomplete sensory experience.

Take a look at Figure

1. Is it just a lot of meaningless

blots? Try turning the

page upside down. What now?

The image is poor, but its

meaning is clearly being

supplemented by what you already

know and “filled out” to

a meaningful thing.

Somewhere in our heads

is a vast store of experience

and knowledge, one function

of which is to activate and

control our perceptual filter.

Stop and give some thought to

the implication of this for

teaching and learning. You

may be the provider of stimuli

during teaching, but how does

the student filter what you provide? If essential previous

knowledge or concepts or language is missing, how will this

affect what your students take out of what you say? Will

they miss essentials and grasp peripherals? Will they remember

the bangs and pops of a demonstration and totally

fail to grasp what you were trying to teach? Will your clever

graphics, trying to convey a three-dimensional structure on

a flat computer screen, fail because the students are not familiar

with drawing conventions or are incapable of generating

three dimensions mentally from two-dimensional

stimuli or even of seeing “near” things far away and vice

versa (1)?

You may be the

provider of stimuli

during teaching, but

how does the

student filter what

you provide?

Figure 1. Meaningless blots?

Turn the page upside down and

look again.

Vol. 74 No. 3 March 1997 • Journal of Chemical Education 263

Chemical Education Today

Figure 2. Information processing model.

Let us move deeper into the model by considering what

happens to the stimuli and information we admit through

the filter. It is thought to pass into a working space (or working

memory) where it is held and manipulated before being

rejected or passed on for storage. This part of the processing

train has been thoroughly researched by workers such

as Baddeley (2) and has given rise to a much more complex

model than I am presenting here. Readers might want to

pursue this further, but a simplified version will suffice for

the present purpose.

The working space has two main functions. It is the conscious

part of the mind that is holding ideas and facts while

it thinks about them. It is a shared holding and thinking

space where new information coming through the filter consciously

interacts

with itself and

with information

drawn from longterm

memory store

in order to “make

sense” (Fig. 2).

H o w e v e r,

there is a drawback.

This working

space is of

limited capacity

and I have written

about this before

in this Journal

(3). It is a limited

shared space

in which there is

a tradeoff between

what has to

be held in conscious memory and the processing activities

required to handle it, transform it, manipulate it, and get

it ready for storage in long-term memory store. If there is

too much to hold, there is not enough space for processing;

if a lot of processing is required, we cannot store much.

It is easy to show this experimentally. Before you read

further, get two pieces of paper or card and cover the right

column of Table 1 and all of the left column except the first

line. Here is an experiment you can try on yourself. The

table shows a date in words, “Seventeenth of March”. Do

this entirely in your head (no writing). Convert the date

to numbers and arrange them in numerical order from

the smallest to the largest. Step one, memorize words and

look away. Step two, translate to numbers 1, 7, 3. Step

three, rearrange numerically 1, 3, 7. That was easy! Now

uncover the next date for 2–3 seconds, cover it, and repeat

the processes above. Check your answer in the right column.

Work your way down column one until your “brain

begins to hurt”.

There is a cutoff at the point where the effort of holding in

memory conflicts with the two thinking processes of translating

and rearranging. The shared space is overloaded. In

practice, it is so uncomfortable to work up to the limit that

we operate below it, thus limiting the working space even

further. How well did you do in the experiment?

What are the implications of this for learning? Not only

do students filter what we give them, but there is a limit

on the quantity they can process and this also has a time

factor included. Does this mean that we are “crippled” by

this mental limitation or can we expand the working space?

The evidence is that we cannot expand the space, but we

can learn to use it more efficiently. A simple example is seen

when children are learning to read. At first every letter is a

piece of information

that

has to be processed

into

words and then

into a sentence.

To begin with,

H-O-R-S-E is

five pieces of information,

but

soon the child

rolls this together

into one

word HORSE

(one piece of information).

In

its first form,

the name is occupying

five

bits of space

but later it uses only one bit of space. Later whole sentences

can coalesce to one space, or at least the sense or message

of the sentence takes only one space. This process is called

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