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!