bennnnkkjgeswaqopfkhrkdofogfdhhgddrtykjgur.ppt

How do high achieving
lower-secondary students
understand the nature of
science?
Dr. Keith Taber
University of Cambridge Faculty
of Education

Why the nature of science?
It has been suggested that the nature
of science provides a suitable focus
for challenging more able students in
science.
(e.g. Gilbert - APECS seminar)

Background
• Work on ‘Explanations’ (APECS Seminar)
• KS3 Strategy - invitation to work on project
• Gatsby SEP support for project
• Constraints:
– Ideas and Evidence (project brief)
– KS3 (project brief)
– ITT (project brief)
– more able students (Cambridge)

Outcome
“Teaching Ideas and Evidence in Science at
Key Stage 3”
SEP / UoCambridge / IoE / KeeleU / KCL /
UoYork
resource: “information and activities for
teaching about ideas and evidence in
science, especially at KS3”
on CDROM (available from SEP)

Cambridge focus
The Cambridge project was initially mooted
as extending work on ‘explanations in
science’;
but became conceptualised in terms of
thinking about developing a suitable
Curriculum Model for teaching about the
Nature of Science.

Cambridge Project
• part 2 (sic): individual trainees to attempt to
explore aspects of teaching about Ideas and
Evidence in Science at KS3,
• and to write-up their ideas/activities for the SEP
project: -
– Tom de Trafford
– Martin Koch
– Tamsin Lowe
– Susan Millins
– Teresa Quail

and part 1?
• To prepare trainees for going into school and
undertaking a project
• Including: arranging for the research team (*) to
collect some ‘benchmark data’ Vicky Asbury
– * Susie Bentley (B); Ann D'Souza (B); Tom De
Trafford (P); Stephen Diston (P); Emily Harris (B);
Scott Horsley (S); Martin Koch (P); Tamsin Lowe
(B); Steve Mason (P); Susan Millins (S); Teresa
Quail (P); Cliff Webb (P); Gordon West (S)

Visits
• To 2 local schools
• Y7 and Y8 top sets in an independent
school
• Y9 top set in a maintained city community
college

Data collected
• A questionnaire was written to survey
students’ understanding of 4 key terms -
theory, hypothesis, experiment, model
• A group task was prepared to explore
students’ understandings of why scientific
ideas develop

background
• The teaching of ‘ideas and evidence’ within
Sc1 of the English NC had been identified as
an area where good practice was not
widespread
• research evidence suggests that secondary age
students often have poor understanding of
such basic features of science as theories and
models (but not focused on the high achievers)

purpose
Within the SEP project the main purpose of
the visits was to allow the research team to
find out at first hand just how sophisticated
lower secondary students’ thinking about
these key areas is, and so familiarize them
with the likely level of understanding
among the students they would work with
on placement.

procedure
• The 2 visits took place on two successive
Fridays in March 2004:
• The research team met in Faculty to discuss
the protocols to be used;
• then went in to the school;
• then met up again in Faculty to review the
visits and the data collected.

The questionnaire
The questionnaire was based around 4 key
terms:
• theory
• hypothesis
• experiment
• model

theory
• 1A) Have you come across the word
‘theory’ in science? (and if yes)
• Can you explain what a theory is?
• 1B) Do you know any examples of
scientific theories?:

hypothesis
‘hypothesis’ in science? (and if yes)
• Can you explain what a hypothesis is?
• 2B) Could you suggest an example of a
hypothesis?

experiment
‘experiment’ in science? (and if yes)
• Can you explain what an experiment is?
• 3B) Can you give any examples of
experiments that scientists have done?
• 3C) Can you tell me about an example of an
experiment that you have done in science?

model
‘model’ in science? (and if yes)
• Can you explain what a model is?
• 4B) Can you tell me about any models you
have seen or used in science?

the group tasks
• The groups were asked to work on one or
more topics (there were eight available)
• In each case they were given an example of
ideas that have changes over time
• And why
– people might have held the original idea
– scientists no longer thought this
– and why they now thought what they did

sight
• Some people used to think that when we see our
eyes send out beams that scan the world around
us. When the beam hit an object, then we would
see it.
• Scientists no longer think this is how we see.
Scientists now believe that for us to see an object
there must be light travelling from the object to
our eyes. The light does not come from our eyes,
but from a glowing (‘luminous’) source, such as
the sun.

sight
• Why do you think people might have
thought that when we see our eyes send out
beams?
• Why do you think scientists now think this
idea is wrong?
• Why do you think scientists now believe that
when we see there must be light travelling
from the object to our eyes?

burning
• Some people used to think that materials would
burn (would be ‘combustible’) if they contained a
special substance, phlogiston. It was believed that
the phlogiston escaped during burning.
• Scientists no longer think that phlogiston exists.
Scientists now believe that burning occurs when a
substance reacts with oxygen.

burning
thought that a substance was released
during burning?
idea is wrong?
burning is a reaction with oxygen?

the solar system
• Some people used to think that the sun and
planets moved around the earth.
• Scientists no longer think that the sun
moves round the earth. Scientists now
believe that the earth and the other planets
all go round (‘orbit’) the sun

the solar system
thought that the sun and planets moved
around the earth?
idea is wrong?
the earth goes around the sun?

the 4 elements
• Some people used to think that everything on
earth was made of four elements called earth,
water, air and fire. All materials were thought to
contain a mixture of these different elements.
• Scientists no longer think that that earth, water, air
and fire are the elements. Scientists now believe
that all substances are made from a much larger
number of elements (such as oxygen, carbon,
hydrogen, iron, copper, nitrogen, sulfur, helium
etc.)

the 4 elements
thought that everything was made up of
earth, water, air and fire
idea is wrong?
there are a large number of elements?

new life
• Some people used to think that small animals,
such as flies and worms, could be produced from
non-living (‘inanimate’) materials such as dirty
rags, old meat or piles of leaves.
• Scientists no longer think that living things can be
produced in this way (by ‘spontaneous
generation’). Scientists now believe that creatures
such as flies and worms are always produced by
parents similar to themselves.

new life
thought that small animals could be
produced by ‘spontaneous generation’?
idea is wrong?
creatures are always produced from
parents similar to themselves?

origins
• Some people used to think that the types (‘species’)
of animals and plants on earth today are just the
same as those that have always been here.
• Scientists no longer think that species have never
changed. Scientists now believe that over a very long
period of time (thousands of millions of years) all
the animals and plants on earth today have
developed from the same very simple living things.

origins
thought that the same types of animals and
plants have always been on earth?
idea is wrong?
species have changed (‘evolved’) over many
millions of years?

moving continents
• Some people used to think that the surface
of the earth has been largely the same for
thousands of millions of years.
• Scientists no longer think the earth’s surface
is fixed. Scientists now believe that the
surface is divided into very large pieces
(‘plates’) that slowly move around, so that
the continents slowly change their positions.

moving continents
thought that the earth’s surface was fixed
and unchanging?
idea is wrong?
• Why do you think scientists now believe
that the continents can slowly move around
the earth’s surface?

blood circulation
• Some people used to think that the heart kept the
body warm by producing warm blood and
pumping it to the rest of the body.
• Scientists no longer think the heart makes blood.
Scientists now believe that the heart pumps the
same blood around a complex circuit of blood
vessels, many of which are too small to be seen.

blood circulation
thought that blood was made in the heart,
and then pushed out to the rest of the body?
idea is wrong?
the same blood passes round and round the
body?

findings
understanding key
nature of science terms

‘theory’
pupil response Y7
n=19
Y8
n=17
Y9
n=28
*
n=64
idea/what people think 9 8 21 38
uncertain/no proof 2 4 7 13
explanation 3 3 5 11
how something works/happens 3 5 3 11
answer/solution 0 4 2 6
prediction 2 0 4 6
equation/formula/maths 0 2 2 4
do not know 4 0 0 4
hypothesis 0 2 2 4

examples of scientific theories
pupil response Y7
n=19
Y8
n=17
Y9
n=28
*
n=64
gravity/Newton 8 5 7 20
Darwin/evolution 5 6 5 16
Einstein/relativity 5 5 6 16
none 4 0 4 8
big bang 2 1 2 5
Pythagorus’ theorem 0 4 0 4
Hooke’s law 0 3 0 3

‘hypothesis’
pupil response Y7
n=19
Y8
n=17
Y9
n=28
*
n=64
prediction 8 14 9 31
no 2 0 8 10
theory 0 0 5 5
yes (can’t remember/explain) 0 1 3 4
aim of experiment 1 2 1 4
explanation 2 0 1 3
idea 0 0 3 3
summary/conclusion 3 0 0 3
way do experiment 3 0 0 3

an example of a hypothesis
year 7 8 9
yes – acceptable suggestion 7 12 2
yes – unacceptable suggestion 5 4 5
yes – unclear suggestion 0 1 2
total yes 12 17 9
no/no response 7 0 19
total 19 17 28

acceptable hypotheses
• I think the magnesium will get heavier
when it’s heated because it’s oxidising and
oxygen has to weigh something (7B1)
• You thought you had water. You do a pH
test to see if you are right. If pH7 you have
proved [sic] your hypothesis (8C3)
• Salt will dissolve in water. (9L2)

not acceptable
• Chucking off a brick and piece of plastic off a
building. Whatever has most damage is the worst. We
found out that the brick was the hardest, because it
shattered the least. (7A1)
• I think a lot of people who smoke get cancer, because
a lot of people who smoke have/get cancer. (8F3)
• If they [!] give you an activity that you’ve got to do
(9K2)

experiment
year 7 8 9
satisfactory suggestion 5 6 10
unsatisfactory 14 11 18
total 19 17 28

satisfactory (experiment)
• If you had an idea you would design an
experiment to see if your idea is right. A
test to see e.g. if something has oxygen or
hydrogen in it. (7E2)
• Trying [sic] to prove [sic] a hypothesis
through a practical. (8D3)
• Testing if your hypothesis is right. (9L1)

unsatisfactory (experiment)
• Where you take apparatus, follow list of
instructions using apparatus and looking to
see if change happens. (7F2)
• It is when you are trying to find out
something about whatever. (8C3)
• To test something to see how it works and
investigate it (9K4)

scientists’ experiments
pupil response Y7
n=19
Y8
n=17
Y9
n=28
testing 5 4 3
an activity/exploration 7 13 12
demonstration 4 - -
design 1 - -
discovery/observation 1 2 4
product - - 3
no details given 2 1 1
no suggestion 5 2 9

experiments as testing
• Doctors have made medicines and scientists
find out whether they work. (7A2)
• Prove oxygen needed to live. Rat put under
glass bowl with water and seen how long it
lasted. (8E3)
• Galileo – lead balls of Pisa tower – check if
gravity has same effect on all objects (9N1)

experiments as
exploration/activity
• Tied a key to a kite strong to experiment
with lightning. Adding acids to various
things. Rubbing a balloon against your hair
(static) (7B1)
• Beagle 2 going to Mars (8D3)
• Newton experimented with light and
prisms. Gravity – dropping objects from
heights (9M1)

experiments as
discovery/observation
• Find electricity – kite – when lightening
struck found lightening was a form of
electricity. (7E1)
• Apple on Newton’s head. (8G2)
• Alex Fleming – penicillin (9R2)

students’ experiments
pupil response Y7
n=19
Y8
n=17
Y9
n=28
testing a question 4 9 7
applying a ‘test’/finding a fact 3 2 11
exploring 13 4 3
activity 6 8 13
making something 0 1 1
demonstrating 0 0 1
no suggestion 1 0 0

testing a question
• heating magnesium in air – does it get
heavier or lighter. Found it got heavier.
(7G1)
• Put an iron nail in 3 different types of test
tube. 1 water and oil on top; 2 just water; 3
Something to take water out. See which
ones rusted and why. (8C4)
• Testing pondweed for photosynthesis (9K2)

experiment as exploration
• Heating up water in test tubes. Putting
different metals into it and seeing how they
reacted (magnesium). (7A1)
• Sodium, calcium and water to see reactions.
(8J3)
• electric circuits – finding out about parallel
and series circuits (9Q2)

experiment as activity
• Adding (sulphuric) acid to baking powder
(foams up). (7B1)
• Sodium, calcium and water to see reactions.
Plants – photosynthesis producing bubbles
(8J3)
• Universal indicator – and the pH scale –
acid and alkali (9O3)

carrying out a test
• Test for starch in fruit – using iodine. Tested
conductors and insulators. Used ammeter to give
voltage (7E2)
• Starch experiment – Benedict’s solution – iodine
test. Acidity of something. Burning off gases – see
what it is – lime water for CO2. (8G3)
• Experiment to test if something is acid or alkali
(9L2)

remember seeing models in science
year 7 8 9
yes 12 13 22
unsure 0 0 2
no 7 4 4
total 19 17 28

explaining models
pupil response Y7 Y8 Y9
exemplar 3 3 4
something made/shaped 3 4 3
credit-worthy 1 2 7
scale/replica 2 2 5
a structure 2 1 1
pattern or diagram 0 1 1
fact 1 0 0
unclear 0 0 1

credit-worthy responses
• Made to look/explain physically what
something is. (7J2)
• Simulate atoms and molecules. Example
thing – to show you the way something is.
(7G1)
• Structure which represents something else
(8F4)
• …

• structure model (9S2)
• Object simulating something in existence
(9M1)
• Not in science lessons, but - it’s how
someone presents the results of an
experiment in a multimedia way. (9U2)
• …

• It’s an example of something that
symbolizes something you can’t get. Too
big or too small. (9L1)
• Hypothetical: simplified, general idea.
Thinking of things would be (9O2)

exemplar
• Model experiment: you do it to show to
others how to do it, Model: how to set up
experiment. (7A1)
• What trying to aim for –model result.
Guidelines for what working towards.
Something to compare to. (8G3)
• An example of something, made from
material to show (9U1)

something made/shaped
• Something you make – creates a 3D object,
maybe of a cycle. (7D2)
• Something that someone’s made. 3
dimensional – you have to make it, you
can’t write it down. (8A3)
• Object you create by using different
materials (9S1)

scale/replica
• Smaller version of e.g. the solar system – so
you can look at it in detail. (7F1)
• a fake – see it but it is not real (8I4)
• Something built, version of something not
the real thing. (9O1)

models met in science
pupil response Y7
n=19
Y8
n=17
Y9
n=28
particles/atoms/molecules 4 0 16
model experiment/apparatus 2 2 1
skeleton 3 1 0
cells 1 0 2
eye 3 0 0
dinosaur 0 3 0
body 1 1 0
globe 1 0 1
heart 1 1 0

models met in science
• other examples mentioned once each:
– car
– circuits
– clocks (in DT)
– computer programme
– head
– solar system
– steam engine

One Y7 student
• ‘Plasticine’ and sticks made atoms
• Model of eye – different parts
• skeleton model
• OHP – heart pumping blood around. (7E2)

provisos?
• these results must be treated as provisional:
– sampling
– data collection method
• unknown how much more detail/explanation
students could have provided
• ‘in situ coding’
• imperfect independent measures!
– inexperience of research team

however
• in general students seemed to have
awareness of these terms, but to be vague
about their meanings
– theory not distinct from theorem, low, hunch,
hypothesis etc.
– experiment perhaps seen as any practical
activity
– model taken as everyday meaning, and many
examples in science not recognised as such

findings
(an overview of themes)
changing ideas in science

how do students explain
changing ideas in science?
• Some of the group responses were at a fairly
superficial level:
– people used to be ignorant/simpler
– then they developed technology,
– and did lots of research…

ignorance
• Hundreds of years ago people liked simple
ways of things working and so never thought
that maybe the earth’s crust was broken up
and moved…(Y8)
• because they had no idea of science at all.
(Y9)

but things are better now!
• People used to think that the same species of plants
& animals had always been on earth, because they
didn’t understand evolution & religion dictated
everything.
• Scientists now know this is wrong because religion
doesn’t dictate everything and we now have a better
understanding.
• We now believe that species have evolved over
millions of years because we now have a better
understanding than before. We also now have a
better understanding of evolution. (Y9)

we have technology
• Because they did not travel around and they
did not have advanced technology. They all
believed in God and didn’t know much
about science. (Y7)
• because they have the technology to work it
out (Y9)
• New technology proves otherwise (Y9)

it’s all down to research
• People only thought this because it was the only
elements they experienced, and this was the only
reasonable theory they could come up with.
• Because they have more scientific knowledge
about the elements and also because of research
they can prove these points.
• Because of discovery and research. (Y9)

or new theories
(but where did they come form?)
• They [now] understand about gravity, and
Keppler’s law of planetary motion. They
understand orbits. (Y8)
• the plates of the earth are pulling the
various continents around the earth. (Y9)
• Because animals have adapted to live on
earth. also plants. (Y9)

However,
• many of the responses were more
sophisticated
– explaining that people had made reasonable
inferences,
– given lack of evidence,
– and that new evidence (due to specific research
and new technology)
– leads to new inferences

lack of evidence
• They thought this because people only
recognised and knew certain types of animals.
They didn’t also know about hybrids and how
species can change. They thought that these
animals may have existed for a long time
looking like they did as they saw them. They
hadn’t found fossils, Also animals has adapted
to their surroundings over the years causing it
to be survival of the fittest (Y7)

lack of evidence
• …When the continents do move it is not by a great
distance and so it wouldn’t be obvious that the
crusts were moving anyway. There are also no
obvious signs that the earth is broken up into
plates as the joints of the crust or plates are hidden
generally. At times you can see the joints (San
Andreas fault) but no others are that obvious. It is
also quite a strange idea so people might not like
to believe that. (Y8)

reasonable inferences
• People thought that phlogiston was released because
burning is obviously hot, and hot air rises so they
thought that to burn, a substance had to be in the
material that would rise and escape. (Y7)
• Small animals such as flies are layed [sic] in things
like old meat. As they only saw the flies after they
had hatched and appeared from the meat they
assumed that the meat ‘gave birth’ to them. (Y9)

new evidence
With the basic forms of dissection available at the time,
scientists could see that blood moved round the body with the
heart pumping it. They could not see that it was produced in the
bones, so it stood to reason that this big, pumping organ would
also be producing the blood. Scientists can now work at the
cellular level, so they eventually found out that the heart had no
parts to produce blood, whereas the bones did. They also found
that the idea of the blood flowing outwards only was
impractical, where would it go? Then there was the structure of
blood vessels, with blocks to prevent it going the wrong way. …
we could now use tracking methods such as putting a dye in the
blood, and having examined the heart we know it has an ‘in’
tube too. (Y9)

new evidence and ideas
Evolution takes so long that it will pass unnoticed. They
did not have knowledge of genetics to know species
might change. Creation theories would have been like
religion, dominant in people’s lives. Evidence in fossils.
Knowledge gaining in genetic field. Development to
overcome natural barriers. Explanation of where the first
life came from. Development/increase in knowledge
related to evolution, genetics, fossil records etc. Work
on inheritance, DNA, mutation. Those theories fit with
the evidence unlike Creation theories etc. (Y9)

evidence from new techniques
• Sent out satellites and observed space, finding out
earth revolved around Sun. They have used
telescopes. They discovered gravity and realised
the larger objects had more gravity. (Y8)
• Because we now have satelite [sic] pictures of the
earths continents moving around[!]. Scientists can
see things changing over years when they write
down their results. (Y7)

so now we know!
• Because they can prove it and monitor it for hundreds
of years. (Y7)
• Sattelites [sic] have also monitored the earth’s
movement and have proved the old beliefs wrong. (Y7)
• They have proved that, theoretically, all things can
BURN. (Y9)
• Scientists now believe this because they have
conducted experiments to prove it and have found that
things don’t burn in other gases. (Y9)
• because they have done lots of experiments/research to
prove all these elements exist (Y9)

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