Transcript Scientific Method

Scientific Method
A. Scientific Method
Scientific method: An orderly, systematic
method for solving problems.
1. Identify a problem
2. State observations about the problem
3. Form a hypothesis about the problem (if…then…)
4. Design an experiment to test the hypothesis
5. Collect data
6. Form a conclusion
7. Retest
B. Hypothesis Versus Theory
Hypothesis
a tentative and testable statement that must be capable of being supported or
not supported by evidence.
Theory
a well-established and highly reliable explanation, but may be subject to
change as new areas of science and new technologies are developed.
Scientific Theories
are subject to change as new areas of science and technologies are developed.
B. Hypothesis
1. A suggested solution to the problem.
2.
Must be testable
3.
Sometimes written as If…Then… statements
A. Hypothesis example: I think ________
because ___________, or If _______, then
__________.
4. Predicts an outcome
5. An example of a hypothesis might be that the
salamanders have curved tails due to a
pollutant in the moist soil where they live.
C. Experiment
1. A good experiment will only
have ONE variable!
2. An experimenter changes
one factor and observes or
measures what happens.
3. It is best to make several
trials.
C. Experiment
4. A well designed experiment should include:
A. Experimental variable: the factor that is
manipulated.
B. Experimental group: the group that receives
the experimental variable.
C. Control variable(s): the factors that remain
the same in all test groups.
D. Control group: the group that does not
receive the experimental variable; this group
is used for comparison.
D. Controls and Variables
1. Independent Variable - IV: the independent variable is
the situation the scientist manipulates.
2. Dependent Variable - DV: the dependent variable
changes in response to the IV and provides the data
measured by the scientist.
3. Constants: These conditions must stay the same so they
won’t interfere with the test results.
4. Control Group: Results from experimental group are
compared to this.
E. Data – Quantitative & Qualitative
1. Results of the experiment
2. May be quantitative (numbers) or qualitative
3. Qualitative: includes descriptions of observations made
during the experiment.
i. It can also include drawings, sketches or side notes
similar to what you would write in a journal.
4. Quantitative: Number data from measurements a scientist
takes during an experiment is logged into a data table and
translated into the appropriate graph.
E. Data – Graphs and Tables
5. Graphs and data tables:
A. Graphs:
I. Use graph paper
II. Give your graph a title and a number.
III. The title should be underlined , specific, and
to the point. It should include the independent
(manipulated) and dependent (responding)
variables of your experiment.
IV. Label on each axis.
E. Data - Graphs
V. Remember: MIX, DRY for graphing
D = dependent variable
R = responding variable
Y = graph information on the vertical axis
M = manipulated variable
I = independent variable
X = graph information on the horizontal
axis
E. Data - Graphs
B. Types of Graphs:
I. A line graph is for response to a
stimulus or change over time.
II. A bar graph is for comparing
several items.
III. A pie graph is for comparing
percentages.
E. Data - Tables
C. Data Tables:
I. Give your data table a title and a number.
II. Title should be underlined.
III. Always use labels to describe the rows
and columns
F. Review: Hypothesis or Not?
1. Albert Einstein was the greatest scientist
in history.
i. No. This is an opinion & cannot be tested.
2. If a person takes vitamins each day, they
will be healthier.
i. No. Cannot measure “healthier.” If more
specific, such as “will have less cholesterol”
and specified which vitamin, then it could be
tested.
F. Review: Hypothesis or Not?
3. If a person plays the lottery, they will become rich.
i. No. This is a prediction, not a testable statement.
4. Children who don’t watch TV are smarter than
children who do watch TV.
i. No. Too general; could not be tested.
“Smartness” is too general, as well as “children who
watch TV.”
If more specific, i.e.: “Children who watch more than
10 hours a week of TV will score less on the state
achievement test than children who watch less than 10
hours a week of TV,” then it could be tested.
F. Review: Hypothesis or Not?
5. Bacteria will grow more quickly in a warm
environment than a cold environment.
i. Yes. This is testable and has a clearly
identifiable independent variable (temperature)
and dependent variable (bacteria growth).
6. A plant grown with salt added to its soil will
be shorter than a plant grown with no salt
added to its soil.
i. Yes. It has a clear independent variable (salt or no
salt in soil) and dependent variable (plant height).