INVESTIGATION AND EXPERIMENTATION
(I & e) :
What is “Science”?
Observations, Inferences, and
Controlled Experiments
1. Science is an attempt to explain
natural phenomenon.
2. All scientific knowledge is based on
accurate observations of the natural
world.
3. -An Observation an act of carefully watching
something and collecting facts.
-Observations are:

Gathered by using our senses (qualitative)

Can also be gathered by taking measurements
(quantitative)
-Characteristics of good Scientific Observations:

Accurate – Quantify or measure whenever
possible

Detailed and Complete – Consider all parts of
the observation

Repeatable – All observers see the same thing
or each time the event is observed the
description is the same
4. There are two types of observations:

a) Qualitative Observations—An observation
that describes the physical characteristics or
qualities of something.
(Ex. The water is hot; The M&M is small; The egg
smells bad; The leaf is orange, etc)

b) Quantitative Observations—An observation
that is based upon numerical information or a
measurement of some type.
(Ex. The water is 45ºC; The M&M is 1.7 cm in
length; The car is traveling at 65 Km/hr)
5. Good scientific observations are used in
order to make predictions, or inferences,
about the natural world.
6. To infer means… to make a prediction based on
observation.
7. An inference is a conclusion that is formed by
using logic and what is previously understood
about the natural world.
Ex
8. Which statement is an inference?
a. It has 3 candles.
b. It is a cake for some one turning 3 years old.
c. It is a round cake with squiggly black lines.
9. Good scientific inferences:
a) Consider all available observations.
b) Fits the understanding of the natural world
c) are the most logical and rational conclusion
10. All inferences must be based on
previous observations of the natural
world.
11. Inferences are the basis for all Scientific
Theories and Hypotheses.
12. What’s the difference?
Theory vs. Law vs. Hypothesis
**A scientific theory is a well-tested
explanation that unifies a broad range of
observations.
(Ex: Theory of Plate Tectonics, Atomic Theory, Cell
Theory, etc.)
-A
scientific theory may be revised as new
evidence is presented.
-A theory is like the automobile.
-WHY?? Components of it can be changed or improved upon, without
changing the overall truth of the theory as a whole.
Scientific Law
**A scientific law is a consistent principle that is
repeatedly observed in nature and is usually
mathematical.
-It is always true.
(Ex: Gravity, Speed of light, the laws of thermodynamics,
Boyle's law of gases, the law of conservation of mass and energy. )
A scientific law is like a slingshot.
WHY?? A slingshot has but one moving part--the rubber band. If you
put a rock in it and draw it back, the rock will fly out at a predictable
speed, depending upon the distance the band is drawn back.
Scientific Method and Controlled Experiments
**A hypothesis is a testable possible
explanation of an observation.
-In science, a hypothesis is useful only
if it can be tested.
-Scientific hypotheses are most often
tested by the process of
experimenting.
An attempted explanation needs to be
tested to be accepted.
Scientific Method
I. Make Observations
II. State the Problem
III. Form a Hypothesis
IV. Set up a Controlled Experiment
V. Record and Organize Data
VI. Formulate a Conclusion
Scientific Method
I. Make Observations – Qualitative
and/or quantitative. Allows to
formulate a question.
II. State the Problem— Form of a
question that indicates the
purpose of the investigation.
III. Form a Hypothesis— A possible
answer to our question

Or a possible explanation about an
observation.
(Hypotheses are not proven but
supported by evidence)
*IV. Set up a Controlled Experiment—
An experiment is basically a comparison
of two situations.
One of the situations is left constant,
while one factor of the other situation is
changed in order to test the affect of that
specific change.
Control – a set of conditions used for
comparison purposes; can either be original
conditions, real-life conditions, or specific
conditions set by the experimenter
There are three types of factors that may affect an
experiment. These factors are called variables.
1. The factor that is purposely changed by the
experimenter is called the independent variable
(also called the manipulated variable).
2. The factor that changes in response to the independent
variable is called the dependent variable
(or the responding variable).
3. The rest of the factors that the scientists keep the same
in the experiment are called the controlled
variables.
It is important to test the affect of changing only
one variable in order to get accurate results.
**If only one variable is changed and all the other
factors are kept the same then we say that it is a
controlled experiment.
***Uncontrolled conditions can lead to inaccurate
results.
V. Record and Organize Data—
- Data tables, graphs, charts, observations, etc.
VI. Conclusion—
- Indicate whether or not your hypothesis was
correct
- Describe how the data provides evidence for
your conclusion

Perform Calculations
- Identify possible sources of error in your
experiment
If experiments do not prove our
hypothesis


Do more experiments or . . .
Formulate a new hypothesis and start
over!