Why can physics be difficult
to learn…
and challenging to teach?
Phil Scott
Centre for Studies in Science and
Mathematics Education, University of
Leeds, UK.
Fysikermøtet 2005
11 - 14 August 2005 Rica Brakanes Hotel, Ulvik i
Hardanger.
Physics: frightful but fun…
Angell, Guttersrud, Henriksen, Isnes (2004)
Science Education
‘A general feature of physics pupils’ descriptions of their subject is
that physics is regarded as difficult and with a high workload, but
also interesting’.
‘All pupils (grade 12) agree to a great extent that physics is difficult’
‘From our data it appears that physics is different from other school
subjects (notably English and social science) in that it has a
higher workload and a faster progression and is more
conceptually demanding’.
What is involved in learning
physics?



Learning physics involves developing a new way of
talking and thinking about the natural world:
drawing on specific concepts, theories, laws,
mathematical tools, conventions.
This is a way of talking and thinking which has been
developed and validated by the scientific community
It is a way of talking and thinking which must be
consistent with observations and measurements of
the physical world.
What is involved in learning
physics?
Everyday social
language
Scientific
social language
(Spontaneous
concepts)
(Scientific concepts)
…Vygotsky
Why can learning physics
be so:
DIFFICULT?!
Why does the ball fall?
Everyday view:
The ball falls because
you let go of it, and it’s
heavy.
Scientific, physics,
view
The ball falls because of
the gravitational pull of
the Earth.
Falling

Conceptual tools: not ‘heaviness’ of the
object…but the concept of ‘gravity’

Basic assumptions about the nature of the world
(ontological demand):
not a contact force…but action at a distance, ‘the
pull of the Earth’

Nature of knowledge (epistemological demand):
not a ‘one-off’…but a generalisable explanation:
falling, tides, planetary orbits…
Learning physics


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…involves developing a new way of talking
and thinking about the natural world
…always occurs against a backdrop of
everyday ways of talking and thinking
…everyday ways of thinking are referred to
as ‘alternative conceptions’!
BIG and SMALL learning
demands

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Different areas of physics make different demands
Where the learning demand is BIG physics can be
difficult to learn and tough to teach
Where the learning demand is SMALL the physics
seems like ‘common sense’.
Leach and Scott (2002)
Studies in Science Education
Designing and evaluating science teaching sequences
Learning demand: between
the particles

What lies between the air particles?
1. And what is in between
those particles?
Researcher: And what is in between those particles?
Student: Hmm……..space?
Researcher: Tell me more about that.
Student: Well… there isn’t really space because
everything’s made up of something. You can’t just
have something exists. Everything has pieces to it
so it probably couldn’t be space. It could
be….smaller particles? Cos, there couldn’t be
nothing…so there’s probably just ones that can
move around. Smaller ones.
2. What is in that area
between the particles?
Researcher: What is in that area between the
particles?
Student: Erm….probably, as I said before…probably
either smaller ones or…. erm….erm…energy?
Researcher: Smaller what?
Student: Smaller particles.
Researcher: And how are those particles different?
Student: They’re probably from a different substance,
since air’s made up of different chemicals.
Erm….the particles probably change…vary….. with
the substance that it pertains to.
3. And what’s in between the
smaller particles?
Researcher: And what’s in between the smaller
particles?
Student: Well….it couldn’t be nothing. I could guess
that there are probably smaller ones….
cos…erm….I’d love to say air but this is air. So…it
would be….within air. You can’t have nothing. So
you’d have the smaller pieces.
Researcher: And why can’t you have nothing?
Student: Cos I don’t think that there is such a thing as
nothing. Because even air which most people think
is nothing….is made up of nothing…is just
space…empty space. It has pieces to it as well.
Learning about special
relativity
Posner, Strike, Hewson and Gertzog (1982)
Science Education
Learning occurs if a new idea is both
intelligible
and
plausible
‘One source of difficulty in learning special relativity stems
from its lack of initial plausibility to physics students’.
How can two clocks read
different times?
Student: I mean how could they (the clocks)
change? Time only goes at one rate, right?
Student: Yeah, I mean, absolute time, it just
seems to go on at a certain rate everywhere.
It just seems natural that it’s constant
everywhere. I mean, even though you see
these results
Shrinking rods
Student: I see them as being – as changing their
length, or changing their time. But I can’t talk to the
person who’s moving at the same velocity as the
stick and the clock. He’s telling me they don’t
change…I feel they haven’t changed, but the way
I’m looking at them has changed…I guess I’m
allowing for the fact that the person who’s seeing
things at rest, who has his clock at rest, his metre
stick at rest, has [pause] a little more right to say
what is really happening to the sticks.
Student: …the fact that it’s moving makes it appear to
me as if it were foreshortened.
Feynman: on physics learning
…there is this possibility: after I tell you something, you
just can’t believe it. You can’t accept it. You don’t like it.
It’s a problem that physicists have learned to deal with:
they’ve learned to realise that whether they like a theory
is not the essential question. Rather it is whether or not
the theory gives predictions that agree with experiment.
The theory of QED describes nature as absurd from the
point of view of common sense. And it agrees fully with
experiment. So I hope you can accept Nature as she
is…absurd.
Richard Feynman (1985)
QED The strange theory of light and matter
Students’ everyday ideas
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Air is weightless…or has negative weight
Heat is a kind of substance
Matter disappears during dissolving
Particles (molecules) expand on heating
Light travels further in the dark
We see things through light leaving our eyes
Energy gets used up
A force is needed to sustain steady motion
Things fall because they are heavy
Students’ alternative frameworks: Pfundt
and Duit, 1991: Numbers of published papers.
Mechanics
281
Electricity
146
Heat
68
Optics
69
Particles
60
Energy
69
Astronomy
36
Modern physics
11
Chemistry
132
Biology
208
An approach to planning
physics teaching
1.
2.
3.
4.
Identify the key physics concepts to be
taught
Consider the nature of students’ existing
thinking in this area
Analyse the differences between the physics
way of knowing and the students’ existing
thinking: specify the learning demand
Devise teaching approaches to address the
learning demand.
Simple electric circuits


Year 7 pupils (age 11-12 years)
No tuition in high school on electric circuits
Where does the ‘electricity’ come
from?
Students’ thinking: ‘The electricity flows out
of the battery when the circuit is complete’
Physics view: The electric charges originate in
the circuit. When the circuit is completed the
charges start flowing in all parts of the circuit
simultaneously.
The learning demand
From point to point…
 the circuit is initially empty and fills with a
‘substance-like material’ that eventually
reaches the bulb and causes it to light.
 Students use a ‘linear causal’ pattern of
reasoning
The learning demand
To all at once…
 When the circuit is completed the charges are
set in motion in all parts simultaneously
 Students need to use ‘cyclic causal’ reasoning in
which causes and effects co-occur.
Perkins and Grotzer (2005)
‘Dimensions of Causal Understanding’
Studies in Science Education
What to do about it?

The BIG circuit!

The ROPE loop analogy
Key questions
In this circuit, the bulb is lit.
Read each of the statements below about what is happening in the battery.
For each statement, put a tick in one box to show if you think it is correct or incorrect.
Battery
correct
don’t
know
incorrect
(a)
Before the battery is connected, there are no
electric charges in the wire. When the battery is connected,
electric charges flow out of it into the wire.
q
q
q
(b)
There are electric charges present in the battery
and the wires all the time. The battery makes them move
around the circuit.
q
q
q
(c)
Chemical reactions in the battery make electric
charge, which then flows round the circuit.
q
q
q
Institute of Physics:
Supporting Physics Teaching 11-14

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IOP sponsored
to support non-specialists in teaching physics
at grades 7-9.
to strengthen their confidence, understanding
and competence in physics teaching.
CD ROM based
What do you need to know?

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The physics ‘story’
Teaching and learning ‘challenges’
- pupil starting points
- the nature of the learning
demand in different topic areas
Teaching approaches
- demos/practical activities
- analogies/explanations/anecdotes
Structure of the SPT materials
And Einstein…
A human being is a part of a whole, called by us
‘universe’, a part limited in time and space. He
experiences himself, his thoughts and feelings
as something separated from the rest... a kind of
optical delusion of his consciousness. This
delusion is a kind of prison for us, restricting us
to our personal desires and to affection for a few
persons nearest to us.
Our task must be to free ourselves from this prison
by widening our circle of compassion to
embrace all living creatures and the whole of
nature in its beauty.
Physics learning
…as:
breaking free from
‘everyday thinking’…
Physics teaching
…as:
working the GAP between
‘everyday’ and
‘physics’ thinking