Theory
Vs.
.
Experimental Evidence
Undergraduate Students’
Laboratory Practice
Illuminated by
The Philosophy of Science
Rachel Havdala
Guy Ashkenazi
Dept. of Science Teaching,
The Hebrew University of Jerusalem
Motivation
Science students show great difficulties in coordinating
their lab results with the theory they learned in class
Aim
To find ways to enhance the coordination between
theory and experimental evidence
Method
Interviews - students views about the nature of science
Lab reports analysis
Question
Is there any correlation between the students’ views
about NOS and their lab practice?
Personal Epistemology
(Hoffer, 2004)
A continuum in the perception of knowledge
External,
Objective
Constructed,
Source of Knowledge
Subjective
Assessment
Observation
and
Justification for knowing
or
Integration
Reasonability
The main components of
knowledge in science
Experiment
Theory
Theory vs. Experiment
in the Philosophy of Science
Empiricism:
Experiment
Theory

Emphasis on the primacy of objective sense experience.

Experiment is justified by consensus of observation. Theory is
justified to the extent it fits observation.
Rationalism:

Experiment
Theory
Confidence in the mind’s ability to formulate the orderly character of
the world as objective laws of nature.

Theory is justified by reason and logic. Experiment is justified to the
extent it is explained by theory.
Theory vs. Experiment
in the Philosophy of Science
Constructivism:
Source of knowledge

Knowledge is constructed by the individual to make
sense of the subjective experiential world.
Justification for knowing

Justification by “viability” – Coherence between
perception and conception (experiment and theory).
The Analytical Process
Primary analysis


Primary Analysis of lab reports (General chemistry lab for
chemists, consists of 8 lab sessions).
Choosing students for interviews (12 from 2004, 13 from 2005
- 25 total).

Primary analysis of interviews.

Selection of three students :
– Very decisive and consistent views about science.
– Greatest disparity.
– Belonged to the same lab group (from the class of 2004).
Results :
Views about NOS
The dimensions, which showed to be of greatest
contradiction between the three students:
1) The basic component of knowledge in science.
2) The purpose of scientific work.
3) Main characteristics of science.
4) The role of mathematics in science.
5) Science in the students’ laboratory.
Views about NOS
The basic component of
knowledge in science
Q: How would you define a scientific law?
A: It is something experimental, for sure…
Q: What is it based upon?
A: Only on experiment. […] First you need the
experiment and then it will be accurate.
[…] As long as it is proved by an experiment,
it is good.
(Daphne)
Views about NOS
The basic component of
knowledge in science
Q: How does a scientist tries to think? Does he
rely on assumptions or on facts?
A: I believe he has to rely on assumptions. You
cannot know how a substance will behave
in advance. You need to take some
assumptions and try to make facts out of
them.
(Ted)
Views about NOS
The basic component of
knowledge in science
You cannot generalize. Every law has
its own history. If someone got hit by
an apple on his head… Sometimes
the theory comes first, sometimes the
experiment. It's a combination,
always a combination.
(Robert)
Personal Philosophy
Source of Knowledge
Daphne “A scientific law… is generally discovered by
chance, and then you do experiments to verify
it.”
Ted
“Even those natural laws that we don’t know
behave mathematically. This is what I believe.”
Robert
“If I didn’t know that these results are already
known, would it matter to me? It doesn’t
matter – for me it is new… it is my own
private research. For me that is sufficient.”
Personal Philosophy
Justification of knowledge
Daphne “You need it to be objective, not only for you –
everyone should get the same experimental
result. It has to be true for everyone.”
Ted
“Mathematics helps base certain theories, or
invent new ones – you just see that a certain
equation fits a certain experiment.”
Robert
“It is true for now. What was written 200 years
ago was true 200 years ago… When they tell
you the law, it works… If you don’t have a
problem, you will take it for granted.”
Theory vs. Experiment
in the Philosophy of Science
Empiricism:
Experiment
Theory

Emphasis on the primacy of objective sense experience.

Experiment is justified by consensus of observation. Theory is
justified to the extent it fits observation.
Rationalism:

Experiment
Theory
Confidence in the mind’s ability to formulate the orderly character of
the world as objective laws of nature.

Theory is justified by reason and logic. Experiment is justified to the
extent it is explained by theory.
Theory vs. Experiment
in the Philosophy of Science
Constructivism:
Source of knowledge

Knowledge is constructed by the individual to make
sense of the subjective experiential world.
Justification for knowing

Justification by “viability” – Coherence between
perception and conception (experiment and theory).
Results :
Analysis of lab reports
and lab practice
The dimensions, which showed to be of greatest
contradiction between the three students:
1) Stating the objective of the experiment.
2) Emphasis in preparation for an experiment.
3) Looking for sources of errors and analyzing them.
4) Arriving to conclusions (in case of differences
between
the
expected
experimental results).
outcome
and
the
Analysis of lab reports
and lab practice
Preparing for an experiment
“I summarize the theoretical background, write
Daphne the main concepts, read the procedure, so I will
know what is going on in the experiment.”
Ted
Robert
“I concentrated on the main concepts, so at
least I will have the basis. To understand
what it is all about. After I will do the lab,
it will all become clearer.”
“I tried to understand for each step, why I
am supposed to do this or that, why I need
acidic environment, what will happen if not”
Analysis of lab reports
and lab practice
Arriving to conclusions
(Buffers lab report)
[While receiving a buffer capacity which is 1.5 bigger for a
diluted solution] “There is a correspondence between the
buffer capacity and the dilution- the more concentrated the
buffer is, the bigger the buffer capacity.” (Ted)
[While receiving that the capacity of diluted and non-diluted
solutions is the same] “When you compare the graphs of
diluted buffer solutions, it seems that both the solutions
have the same efficiency, since the slope in both graphs is
similar.” (Daphne)
Conclusions
The relative weight each student had in regard to
theory vs. experimental evidence, reflected clearly in
their approach to lab work  high correlation
between the students’ views about NOS and their lab
practice.
Perception of one component as absolute and
objective, and the other as tentative and subjective
might lead to:
Dissociated view of knowledge in science.
Disregard for one component in a case of conflict.
Educational Implications
Integrating epistemological awareness as
component in teaching and instruction:
a
A workshop for lab instructors, based on the
lab reports analysis, using concrete examples
(Under construction).

Providing proper feedback to students on
their lab reports might encourage them to
coordinate theory and evidence.

Thank You
Guy.Ashkenazi@asu.edu