Transcript 1.1.2 Scientific Method - Science at St. Dominics

1.1.2 The Scientific Method
1
In today’s class you should learn
about..
• What the scientific method is and what the main
steps involved are.
2
Homework
• Learn what the following mean: scientific
method, hypothesis, control
• In homework copy Pg 9 Q16
3
The Scientific Method
• The scientific method is one method
that can be used to solve a problem
5
1.1.2 Scientific Method
Observation
Hypothesis
Experiment
Result
Conclusion
If hypothesis is supported
Formation of
Theory and then Law
If hypothesis is not supported
A new hypothesis
needs to be found
and tested
6
1. Observation
• You observe something using your
senses.
• You may come up with a question
that you would like to investigate.
7
The scientist
tries to explain
what caused
what was
observed.
• 2. Hypothesis:
The hypothesis is an explanation for what
a scientist observes. It has to be testable.
.
8
3. Experiment
• You design a fair experiment to test
whether your hypothesis is correct or not.
• You must use a control experiment
• The outcome must be measurable.
• You must do replicate experiments (
.
exact copies of an experiment)
9
Principles of experimentation
This is not a fair test because…
10
Testing
which mouthwash
Control
Group
Petri dish
is better at killing Bacteria grown
-no mouthwash
bacteria on the plates. from swab
What could the control be?
Listerine
Experimental
Group
Wal-Mart
brand
11
• Definition :
• A control experiment is a
standard experiment used for
comparison
12
4. Result
Record and analyze data (information
gathered from an experiment).
13
5. Conclusion
• You state whether your hypothesis
was correct or not
• Try to explain your results.
14
Finally
1. You Report and Publish your results. in a
Journal
2. If a hypothesis is supported by many
experiments it becomes known as a theory.
3. When a theory is supported over a long
period of time then it becomes known as a
Law or Principle.
15
1.1.2 Scientific Method
If hypothesis is supported
If hypothesis is not supported
16
1.1.2 The Scientific Method
Limitations of the Scientific
Method
Today we will …
• Learn about
• How drug trial experiments work
• What the limits of the scientific method
are
18
Limitations of the Scientific Method
• Is limited by what can be observed with our
five senses.
• The basis of the investigation (bad design)
• limitations of our measurement instruments
• may be affected by time pressure for results
19
Limitations of the scientific method
• scientists sometimes make mistakes
• Interpretation of results may be affected
by the emotional involvement of
investigator
• Some problems are solved by serendipity!
20
Check your learning..
• What is the scientific method?
• What are the main steps?
• Define Hypothesis
• What should be involved in a good
experiment?
• Define control?
• What happens after a hypothesis is
verified?
• Distinguish between a theory and a law
• Explain 3 limitations of the scientific
method
21
Drug testing terms
As with every experiment its important to
Use a LARGE SAMPLE SIZE
And use RANDOM SELECTION
Placebo - Control used in drug testing
Single blind test
Either the Scientist or the test subject knows which is the real pill and which is
the placebo
Double blind
• Neither the tester nor the person being tested knows which is the real pill
and which is the placebo.
22
Can you…
• Explain some of the limits of the scientific
method to solve problems?
• Tell why the following are important
Large sample size, random selection,
placebos, single blind testing, double blind
testing
23