CHILDREN CAN GRASP THE IDEA OF THE INNER STRUCTURE OF MATTER

Luigia Bosman
Dipartimento di Fisica-Universita di Pisa
Pisa - Italy

KEY WORDS :- 
- Inner structure of matter 
- Children analyzing matter
 
INTRODUCTION.

The nature and behaviour of matter is a central theme both scientifically and culturally, so it
is included in most primary school science curricula. The subject is one of the many
conceptual areas in science in which children's understanding, before and after formal
teaching, has been explored. It is still a fruitful research area in order to foster more effective
teaching and meaningful learning in the school setting.

Pupils' (aged 7 to 16) conception of matter and its transformations have been carefully
studied by many authors and the results are described in many interesting papers
(Anderson 1990, Stavy 1990, Jones 1989). The authors agree that the pupils (also when they
have completed their compulsory school) have difficulty in understanding concepts such as
atom, molecule, chemical reaction, and changes in the state of matter, which the theme of
matter presupposes.

Nevertheless the children, I think, can be introduced to a first idea of the structure of matter,
namely it is possible to lead primary school pupils to grasp the properties and behaviours
of the objects depend on the inner structure of materials they are made. In order to account
for that following notes are reported (Bosman 1988).


OBJECTS' BEHAVIOUR DEPENDS ON THE STUFF THEY ARE MADE OF

The results of our research work (which since 1976 has been dealing with the teaching of
science and technology to pupils of primary school) show that:

i)   Children are interested in knowing what the objects are made of.

ii)  They're also able to grasp the properties and behaviour of the object, depending on the
inner structure of materials they are made of.

 
Sets of coordinated science activities have been prepared aimed at helping children to
develop scientific abilities and training them to grasp concepts like mass, volume density,
energy, thermal processes and electric current and voltage.

Practical activities and ensuing technical problems also had a part: the pupils were trained
to build tools and instruments necessary to their work, like a sensitive balance,
thermometer, thermostat, water clock, rain gauge, simple electric switches, simple models of
working machines (steam turbine, steam machine, electric motor). (Violino 1987).

Simple technology has been used by primary school pupils to build :

-    House and furniture models, correctly proportioned in order all parts fit together (the
object have used to study top view).

-    Sailing boats made in polystyrene (this work has been the start at grasping the concept
of density.) (Bosman 1989).

-    The working machines had been used to introduce the pupils with concepts of energy
and the like (energy conservation, transportation). (Violino 1987).

-    Simple electric and magnetic circuits have been used to understand concepts (current,
tension, etc......) and working electrical appliances. (Bosman 1986).

All that gave the children the opportunity to realize that different tools must be used for
different manufacturing.

Hereafter an example is given of the interest the children were showing during their work,
and the experiments carried out to satisfy their curiosity.

The pupils of grade 1 (primary school) who were building simple animal models made in
cork and small wood sticks (supporting material for logical and arithmetical activities)
made comments like:

"Cork is easily worked."

"It is easy to drive the toothpick in the cork; if even I fail in driving 
I do it again without bungling."

"Cork is light and makes a slight noise falling down."

"Cork is quite like a sponge, it's full of holes, but if it is dipped into the water, it doesn't
soak."

"Why don't the cork holes allow water to pass through?"

"Perhaps there is no one right through."

"What does cork usually do ?"

"It is used to put on the table the hot saucepan."

"Round pieces of cork are used as stoppers for the bottles."

"Cork is also used to cover the walls of a room, a cinema."

"What is the cork made of ?"


Finally some experiments in which pupils were involved.

A set of objects made of different materials having the same size and/or the same mass has
been tested in various experiments. 

1.   Waterproof
Four equally sized blocks made in polystyrene, cork, plywood and firewood are dipped in
the water : all of them float. The day after the woods were floating just below water
surface. Why?

All blocks are cut down :

The inside of the polystyrene and cork is wholly dry, whereas the inside of woods was
soaked with water.


As an attempt at understanding the results the children have observed :

"Cork, polystyrene, plywood and firewood are light with empty space inside; they are able
to float, but the inside holes of cork and polystyrene don't allow water to pass through."
They also noted : "The inside holes of are tree trunk fibres which provide to soak water and
out through all the plant".

2. Thermal conductivity:
Four equally sized boxes are built of cork,plywood,polystyrene, firewood:four equal ice
cubes are put into each one. The ice inside takes different time to become liquid.

Polystyrene         2h 40m

Cork                2h 20m

Plywood             2h 00m

Firewood           1h 50m

The children observed:"The ice cream can keep for two hours in a polystyrene pack."

Polystyrene and cork are insulating materials better than wood:that could depend on the
form and size of their inside holes. Polystyrene and cork look quite similar.

3. Acoustic conductivity:
A buzzer is put into each box in order to compare the humming of the inside buzzer with
the outside one. All boxes are able to deaden the humming but not in the same way:the cork
is the most deadening whereas the polystyrene is the least. In this case they are rather
different.

Which inside difference does this depend on? The pupils' opinion has been: the polystyrene
inner structure is rigid, like the case of the pocket radio,whereas the cork one is soft.

They noted: "the form and size of the inside holes does not account for the results!"

4. Burning test:
Four equally sized blocks made in polystyrene, cork, plywood and firewood are burnt
down. The results have been:
- the polystyrene combustion remains are coal tar;
- the ash of the wood and cork look quite similar.

The children's opinion has been that the behaviour of the materials could depend on the
kind of the inner components (wood and cork come from the tree) and on their arrangement
(holes).

FURTHER DETAILS.

We have been present in the classroom during most of the activities, both to help the teacher
and to observe the response of the children and follow their progress. They seemed to really
have trust and talk in science because the results of their experiments seemed to agree with
their everyday experiences.

This project was first (1988) tested with 22 primary school pupils of the fifth grade (10-11
aged). The next year six teachers adopted the project in their class (5th) for a total of 146
pupils. Of course new experiments were presented the pupils, e.g. :

- Thermal conductivity of different metals have been observed.

- Equal quantities (masses) of: water + aluminum marbles, water + glass marbles, water +
wood balls, have been heated to boil the water. The times the electric boiler has taken, have
been measured.

The results have been: different times occur for different materials (the times are related to
doing work of electric boiler) so different quantities of heat are needed to increase the
temperature of different materials from T1 to T2. The children could grasp the first idea of
heat capacity, which, they also realized, is quite different from thermal conductivity.

CONCLUSIONS

The children participating in the project have really understood the meaning of the
experiments in which they have been involved. Some formal evaluation has been carried out,
in order to check up the children understanding of the results of the experiments. The
activities proposed have been aimed at interesting the pupils id observing the facts (the
peculiar features of the materials depend on their inner structure), to explain the results and
to carry out new testing experiments. 

During the activities abstract models have never been used; the picture the children have
given of the materials structure has been in terms of the concepts draw on their everyday
experience (size of the inner holes and their arrangement).

The ideas they have got, I think, will be the useful background they need to understanding
concepts like atom, molecule, etc later on. They'll realize that the abstract model can explain
all the facts they have observed, and many different ones.

Finally as concerns the teachers, we noted they have found this project particularly
attractive because of the ready availability of everyday substances and the wide range
activities, which can be performed with little specialized equipment and without theoretic
topics.

Particularly teachers who feel hesitant about taking science because of their lack of
adequate background, could find such a topic non-threatening and useful for achieving
objectives in the areas of process skills, concepts development and attitudes.

REFERENCES

B. Andersson : "Pupils conceptions of matter and its transformations (age 12-16)" 1990
Studies in Science Education.

L.   Bosman, F. Lazzeri, J. Legitimo : "Argomenti e concetti di elettricita nella  scuola 
elementare",  La Fisica nella Scuola XIX 1, 30-36 (1986).

L.   Bosman, F. Lazzeri, J. Legitimo: "Objects' Behaviour depends on stuff they are made of.
 And what are the stuffs made of?", International Conference "Teaching Modern Physics"
Universitat Munchen, September  12-13 1988 Proceedings P. 380.  

L.   Bosman, J. Legitimo, L. Martinelli: "Floating and Sinking". Proceedings of a Europhysics
Study Conference Interdisciplinary Aspects of Physics Education, Altmunster, Austria,30
July - 5 August 1989, P. 353-356.

B.   L. Jones, P. P. Lynch and C.Reesink : "Children's understanding of the notion of solid
and liquid in relation to some common substances" 1989 INI. J. SCI. EDUC. V. 11 n. 4 pp.
417-427.
 
R.  Stavy  :  "Children's Conception of Changes in the state of matter: from  liquid (or
solid) to gas" 1990 J. Of Research in Science Teaching Vol 27  n. 3 pp 247-266.
 
P. Violino  : "Using Elementary Technology to Primary Science" 1987 D. J. Waddington
(Oxford: Pergamon) P 21.