1. The Scientific Method Chapter 2, section 2-1 p.29-31
Robert Boyle
Published The Sceptical Chymist (1661)
…stated that scientific speculation was worthless unless it was supported by experimental evidence.
This principle led to the development of the scientific method.

2. Using the scientific method requires that one be a good observer.
observation inference
uses the five
senses
involves a judgment
or assumption

3. “My mother the eye doctor”
In performing activities and experiments, you make observations. An observation is something you see.
There are times when you make judgments or decisions based on your observations.
In performing activities and experiments, you make observations. An observation is something you see.
There are times when you make judgments or decisions based on your observations.
These judgments or decisions are called inferences. Inferences are logical conclusions based on your observations.
Look at the cartoon above.
Read the statement below the cartoon.
Based on what you observe in the cartoon, decide if each statement is an observation or inference.
One of the teams is called the “Reds.”
Observation or Inference?
The adult is holding a piece of paper.
One player is a catcher.
The mother of the batter is an optometrist or opthalmologist (an eye doctor).
The players in the picture are on opposite teams.
One player is holding a bat.
The adult is the umpire.
The player holding the bat is talking.
The piece of paper is a note from the mother of the batter.
Names are written on the uniforms.
One player is wearing a catcher’s mask.

4. Observations are also called data.
There are two types of data.
Scientists prefer quantitative data over qualitative data. It is easier to replicate and compare quantitative data.
qualitative data quantitative data
descriptions; measurements;
no numbers must have numbers
and UNITS

5. Parts of the Scientific Method
Identify an unknown.
Make a hypothesis
(a testable prediction).
Experiment to test
the hypothesis.
Draw a valid conclusion.

6. Hypotheses A tentative explanation for the observations
May not be correct, but it puts the scientist’s understanding of the system being studied into a form that can be tested
Copyright © Pearson Benjamin Cummings. All rights reserved.

7. Experiments Tests the validity of the hypothesis
Are systematic observations or measurements made under controlled conditions, in which the variable of interest is clearly distinguished from any others
Has control group (lacks the variable you are testing) & experimental group (has the variable you are testing)
Experiments are controlled meaning you can only test 1 variable at a time!
Tests dependent & independent variables
Independent Variable
The variable that will be tested
Dependent Variable
The variable that is affected by the independent variable
If experimental results are reproducible, they are summarized in a law.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

8. A Scientific Experiment
procedure
the order of events
in an experiment;
the “recipe”
variable
any factor that
could influence
the result
Experiments must be controlled; they
must have two set-ups that must differ
by only one variable.
The conclusion must be based on the data.

9. Scientific Method Observations Hypothesis Experimentation
Controlled (one variable changed at a time)
Collect data (quantitative and qualitative)
Analyze data (graph, statistics…trends)
Form valid conclusion.
After many experiments…form a theory.
Recall, our checkbook activity. Each check represented data. As more data was collected it became clearer what had happened. Some bits of data were unimportant.
Most likely, you had to modify your theory as new pieces of data were revealed.

10. Scientific Law vs. Scientific Theory
A law states what happens.
Law of Gravity
A theory tries to explain why
or how something happens.
You can distinguish between a theory and a law by asking the question: Is the proposal measurable?
Yes, the statement is a law.
No, it is a theory.
Theory of Gravity
Atomic Theory
Collision Theory of Reactions

11. Experiments Law Theory – Describes what happens and not why
– A verbal or mathematical description of a phenomenon that allows for general predictions
– Describes what happens and not why
– Unlikely to change greatly over time unless a major experimental error is discovered
Theory
– Attempts to explain why nature behaves as it does
– Is incomplete and imperfect, evolving with time to explain new facts as they are discovered
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

12. Theory vs. Natural Law Scientific theory Natural law
analyze additional data
Hypothesis
analyze initial observations
Experiment

13. Scientific Method Make observation Ask question Develop hypothesis
Test hypothesis
with an
experiment
Test hypothesis
with further
experiments
Revise
hypothesis
Analyze data
and draw
conclusions
Hypothesis IS
supported
Hypothesis
is NOT
supported
Develop
theory
Wysession, Frank, Yancopoulos,
Physical Science Concepts in Action, 2004, page 8

14. Scientific Method An Overview Question Research Hypothesis Procedure/
First
What does the scientist want
to learn more about?
Then
Research
Gathering of information
Scientific Method
An Overview
Next
Hypothesis
An “Educated” guess of an
answer to the question
Then
Procedure/
Method
Written and carefully
followed step-by-step
experiment designed to test
the hypothesis
Next
Data
Information collected during
the experiment
And
And
Observations
Written description of what
was noticed during the
experiment
Finally
Conclusion
Was the hypothesis correct
or incorrect?

15. Stages In The Scientific Method
OBSERVING
collecting data
measuring
experimenting
communicating
FORMULATING
HYPOTHESES
organizing and
analyzing data
classifying
inferring
predicting
communicating
TESTING
predicting
experimenting
communicating
collecting data
measuring
THEORIZING
constructing
models
predicting
communicating
PUBLISH
RESULTS
communicating
Data do not support
hypothesis – revise
or reject hypothesis
Results confirmed by other scientists –
validate theory.
There is an organizational scheme to the scientific method. However, students should be aware that this scheme is NOT a set of procedural steps that are strictly enforced.
Why is it so important to present scientific results in a form than can be evaluated by others?
(Verification of results is the only way we can have confidence in the findings of scientific research.)
Which stages shown involve data?
(All stages shown involve data.)
What might be wrong if repeated experimentation does not support a hypothesis?
(The hypothesis may be incorrect.)

16. Laws of nature never change.
Scientific Law
Charles’s
Law
V1 V2
T1 T2 =
Observations
Scientific Law
Experiments
NEED TO CHANGE:
picture of balloon over hot water bath (can have mouse over where balloon is small and large),.
A scientific law summarizes the results of many observations and experiments.
Laws of nature never change.

17. Theories and Laws The Earth is flat…
Speeding kills (Audubon, Germany);
seat belts save lives…
LAW: 65 mph and wear seat belt
No explanation of why…but the theory is if you drive at 120 mph and crash, an ambulance won’t need to be called (only next of kin).