SCIENCE
Definition of Science A way of exploring and explaining the
natural world Using a process designed to reduce the
chance of being misled
SCIENTIFIC METHOD
PART I:
The Scientific Method Make observations Ask questions Develop a hypothesis Make predictions Test the predictions
Experiment Manipulate variables
Independent Dependent
Conclusions: analyze and interpret results
Peer Review/Publication The “scientific method” is a
formalized version of the procedure any of us might take, using common sense, to resolve a problem.
(Withgott and Brennan, 2007)
1. OBSERVATION
The light doesn’t turn on
2. QUESTION
Why didn’t the light turn on?
3. MULTIPLE HYPOTHESES
What are all the possible answers
(hypotheses) to the question?
Example: The light bulb is burned out
Example 2: ?
4. PREDICTIONS
What data would support a particular hypothesis (= expected
data) and/or what data would refute the hypothesis?
Example: The light bulb will rattle when shaken
5. TESTS (Experiments)Conduct tests to collect actual
data?
Example: Shake the light bulb and record sound
6. TENTATIVE CONCLUSIONS
Which hypotheses were supported (not refuted) by the actual data?
Write up report (introduction, methods, results, discussion) for
publication
7. PEER REVIEW & PUBLICATIONSubmit your report to a scientific journal that is
peer-reviewed, meaning that your methods, data, tentative conclusions will be scrutinized by
scientists whose reputation is at stake if they allow your report to be published.
Publication leads to creation of scientific information
The Scientific Method Scientific
understanding advances through evaluation and dissemination of information to the scientific community.
How does this information get disseminated to the public?
(Withgott and Brennan, 2007)
THE NATURE OF SCIENTIFIC PROOF & KNOWLEDGE
PART II:
Nature of scientific proof Hypothesis:
A possible explanation or statement that might be true and will be tested by the scientific method.
Can be falsified Cannot be positively proven Therefore, hypothesis are accepted not
proven
Nature of scientific proof Example:
Observation: All the swans you have ever seen are white
Hypothesis: All swans are white Test: examine large number of swans Tentative conclusion: all swans are white
(hypothesis accepted) If you looked at a million white swans, there
could still be a black one However, if you found just one black swan,
your hypothesis would be falsified
Nature of scientific proof When a hypothesis withstands RIGOROUS
testing, especially over time, it becomes a theory
Theory: A hypothesis that has been rigorously tested
and over time has become generally accepted by the scientific community as correct
Nature of Scientific Proof Some examples of theories are:
Theory of relativity Theory of plate tectonics Theory of evolution
Eventually theories become laws Law of gravity
Nature of Scientific Knowledge The main body of science is very stable
and grows by being corrected slowly So, although scientists accept that scientific
knowledge is always open to improvement, the main body of knowledge is well-accepted and stable
Scientific Worldview There are several beliefs underlying the
work of scientists: By working together over time, people can
figure out how the world works Knowledge is both stable and changing
Scientists become excited by new ideas, but are skeptics that judge ideas by the strength of the evidence that supports them.
Scientific Worldview The universe is a unified system
functions in accordance with fixed natural laws that do not change from time to time or from place to place
Knowledge gained from studying one part of it can often be applied to other parts of it
All events arise from some cause or causes and, in turn, cause other events.
We can use our senses and reasoning abilities to detect and describe natural laws that underlie the cause and effect relationships we observe in nature.
Are the terms Science and Technologysynonymous?
Science Technology Technology = the application of scientific knowledge for practical purposes.
EXPERIMENTAL DESIGN
PART III:
Experiments--definition A way to test an hypothesis
Experiments—some rules
1. Adequate Sample Size. Ex. Larger sample size better
2. Representative Sample. Ex. Random sample
Experiment—different types
1. Observational experiment
2. Manipulative approach (or controlled study)
3. Natural experiment
4. Theoretical experiment
.
Observational Experiment Systematic study of natural variation
Searches for correlation or statistical association among variables
Examples: Measuring patterns of species diversity across the continent Do the number of herbivores increase with increased plant
numbers & productivity
Challenge: Hard to control variables Hard to determine cause & effect
Benefits: Can be done over large areas of space & time
Manipulative or controlled study Uses a model system to control and manipulate variables An experiment in which variables are taken into account Based on comparing a control group with an experimental
group Both groups are treated identically except for one variable
or factor This factor is changed for the experimental group but not
the control group If an effect is seen in the experimental group but not the
control group that indicates that the factor changed is the cause of the effect
Examples of Controlled Studies Studying the effect of nutrients on plant
growth—add or change the kinds & amounts of nutrients in natural or artificial setting
Studying the effect of grazing on plant communities—exclude grazing on study plots & allow grazing on others
Challenge: hard to do over large scales of space & time
Manipulative or controlled study
Variables: factors that affect observations or experiments Dependent variable—response that is
measured Independent variable—varied or manipulated
by researcher (cause)
Natural Experiment Similar to manipulative study except that
manipulations are caused by natural event such as:
Volcanic eruption Flash flood Fire Pest outbreak
Challenges: hard to control all variables & to know when natural events will occur
Benefits: studying natural events
Theoretical Experiment
Uses logic and mathematical proofs to develop general principles for making and testing predictions
AN EXAMPLE OF A MANIPULATIVE OR CONTROLLED STUDYTHE MEALWORM MYSTERY
MEALWORM MYSTERY
A student conducted 4 experiments to determine how mealworms respond to light and moisture.
All variables except light and moisture were held constant from experiment to experiment.
For each experiment, 12 mealworms were placed in the center of a box and then their positions were recorded 24 hours later.
EXPERIMENT 1
QUESTION: Are mealworms attracted to light?
mealworm
QUESTION 2: Are mealworms affected by moisture?
Answer? You can’t tell; it could be either or both
EXPERIMENT 2
QUESTION: Are mealworms affected by light?
QUESTION 2: Are mealworms affected by moisture?
Answers?
They are affected by light; we don’t know about moisture
EXPERIMENT 3
QUESTION: Are mealworms affected by light?
QUESTION 2: Are mealworms affected by moisture?
Answers?
With just this experiment, it seems they didn’t move
EXPERIMENT 3
QUESTION: Are mealworms affected by light?
QUESTION 2: Are mealworms affected by moisture?
Using the information from the other 2 experiments…
Answers?
Yes and Yes (despite attraction to light, they avoided wet
THE EXPERIMENTS1 2
3
QUESTION: Which variables affect mealworm movement based on the above experiments (note that movement may be either toward or away from something)? A. Light but not moisture. B. Moisture but not light. C. Both light and moisture. D. Neither light nor moisture. E. Can’t tell.
mealworm
Without the controlled experiment we would know nothing!