The Scientific Method
The scientific method incorporates observations,
hypotheses, experiments, theories, and laws.
Observations and Hypotheses
Scientists make observations when they note
and record facts about natural phenomena.
 Definition: A hypothesis is a tentative statement
that proposes a possible explanation to some
phenomenon or event.
 Scientists try to explain their observations by
devising hypotheses.
 A hypothesis is useful if it accounts for what
scientists observe in many situations.

Experiments and Variables
In order to learn more, scientists often perform
experiments in which one or more of the conditions
are controlled while others vary.
 An important principal of an experiment is that it
can be repeated numerous times.
 Scientists will often use a control group to establish
a baseline measure for their experiment. The control
group is identical to all other items or subjects that
you are examining with the exception that it does
not receive the treatment or the experimental
manipulation that all other items or subjects receive.

Experiments and Variables
The variable being manipulated or controlled in an
experiment is called the independent variable.
 The variable being measured or observed in the
experiment is called the dependent variable.
 The observations, which are recorded from an
experiment, constitute data.
 Finally, scientists will use the data collected to draw
their conclusions about the experiment. Either the
hypothesis is supported or it is not.

What if it doesn’t work?
When observations or experimental data do
not fit the hypothesis, it must be scrapped or
adjusted.
 The new or refined hypothesis is then subjected
to further experimental testing.
 Note that while the hypothesis guides the
design of new experiments, the experiments
guide the rejection or refinement of the
hypothesis.

What if it does work?
Once a hypothesis survives the test of repeated
experimentation, it may be elevated to a theory.
 A theory is an explanation of an event that has
been supported by consistent, repeated
experimental results and has therefore been
accepted by the majority of scientists.
 Theories can never be proven, however, they do
give us the power to predict the behaviour of
natural systems under circumstances that are
different from those of the original
observations.

Scientific Laws
A scientific law is a concise statement that
summarizes the results of a broad variety
of observations and experiments.
 A law is different from a theory in that it
only describes a natural phenomena – it
does not attempt to explain it.
 Scientific laws can often be expressed by
simple mathematical relationships.

Theories

Darwin’s Theory of Evolution is the widely held
notion that all life is related and has descended
from a common ancestor. That is, complex
creatures evolve from more simplistic ancestors
naturally over time. In a nutshell, as random
genetic mutations occur within an organism's
genetic code, the beneficial mutations are
preserved because they aid survival.
Theories


Einstein’s Theory of Special Relativity assumes
that the speed of light in a vacuum is the same
for all observers, regardless of their relative
motion or the relative motion of the source
of the light.
Consequences of special relativity include
time dilation and the twin paradox, length
contraction, and the famous mass energy
equivalence (E = mc2).
Laws

Boyle’s Law states that the volume of a
gas is inversely proportional the pressure
exerted on it. Mathematically this looks
like:
PV = k
or V = k / P
Where P denotes pressure, V is the
volume, and k is a constant.
Laws

Newton’s Second Law of Motion states
that a body’s acceleration (a) is directly
proportional the force (F ) applied to it
and inversely proportional to its mass
(m).
a = F/m
or more commonly
F = ma
The Scientific Method In Practice

The following flowchart draws out all of
the steps of the scientific method in their
appropriate order. Please make sure that
you know this chart well before our first
test and also for our final exam.
The Scientific Method Flowchart
Identify The Problem
Observations and Questions
Gather Information
Make a Hypothesis
Perform Experiment
Revise Hypothesis
Repeat Several Times
Hypothesis Supported
Draw Conclusions
Communicate Results
Analyze Data
Hypothesis Not Supported
The Scientific Method Example
Identify
My CarThe
Won’t
Problem
Start
Observations
Have I bought
andgas
Questions
lately?
Gather
No I Information
haven’t.
It will
Make
startaifHypothesis
I put gas in it.
Perform
Put gas Experiment
in the car.
Revise Hypothesis
Repeat
Not Several
Applicable
Times
Hypothesis
Yup. It started.
Supported
Analyze
Did it start?
Data
Draw
CarsConclusions
need gas.
Communicate
Actually,
you might
Results
want to keep this one to yourself.
Hypothesis Not Supported
Homework

Write a short (less than a page)
description of your own example of how
you used the scientific method during the
in class paper helecoptor challenges.
Describe as many steps as possible.