Theory Vs Experimental Evidence Undergraduate Students Laboratory Practice

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 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 Source of Knowledge Constructed, Subjective Assessment Observation Justification for knowing and or Integration Reasonability

The main components of knowledge in science Experiment Theory

Theory vs. Experiment in the Philosophy of Science Empiricism: Experiment Theory n Emphasis on the primacy of objective sense experience. n Experiment is justified by consensus of observation. Theory is justified to the extent it fits observation. Rationalism: n Experiment Theory Confidence in the mind’s ability to formulate the orderly character of the world as objective laws of nature. n 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 n Knowledge is constructed by the individual to make sense of the subjective experiential world. Justification for knowing n Justification by “viability” – Coherence between perception and conception (experiment and theory).

The Analytical Process Primary analysis n Primary Analysis of lab reports (General chemistry lab for chemists, consists of 8 lab sessions). n Choosing students for interviews (12 from 2004, 13 from 2005 - 25 total). n Primary analysis of interviews. n 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 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 n Emphasis on the primacy of objective sense experience. n Experiment is justified by consensus of observation. Theory is justified to the extent it fits observation. Rationalism: n Experiment Theory Confidence in the mind’s ability to formulate the orderly character of the world as objective laws of nature. n 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 n Knowledge is constructed by the individual to make sense of the subjective experiential world. Justification for knowing n 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 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 a component in teaching and instruction: A workshop for lab instructors, based on the lab reports analysis, using concrete examples (Under construction). Ø Providing proper feedback to students on their lab reports might encourage them to coordinate theory and evidence. Ø

Thank You Guy. Ashkenazi@asu. edu