The Scientific Method
Virginia Standard of Learning BIO.1a-m
BIO SOL: 1 a-m
The student will plan and conduct investigations in which:
• observations of living organisms are recorded in the
lab and in the field;
• hypotheses are formulated based on direct
observations and information from scientific literature;
• variables are defined and investigations are designed
to test hypotheses;
• graphing and arithmetic calculations are used as tools
in data analysis;
• conclusions are formed based on recorded quantitative
and qualitative data;
• sources of error inherent in experimental design are
identified and discussed;
BIO SOL: 1 a-m
The student will plan and conduct investigations in which:
• validity of data is determined;
• chemicals and equipment are used in a safe manner;
• appropriate technology including computers, graphing
calculators, and probeware, is used for gathering and
analyzing data and communicating results;
• research utilizes scientific literature;
• differentiation is made between a scientific hypothesis
and theory;
• alternative scientific explanations and models are
recognized and analyzed; and
• a scientific viewpoint is constructed and defended (the
nature of science).
Progression of Ideas in Science
• Hypothesis- a possible explanation
to a question based on information
the scientist has already gathered
- If experiments show a hypothesis to be
correct, other scientists may accept it as
support for a scientific theory.
EX: Plants obtain their energy from the
sun.
Progression of Ideas in Science
• Scientific Theory- a general
statement of why things work based
on hypotheses that have been tested
many times
Progression of Ideas in Science
- Theories are used to explain & predict
the outcome of other experiments
- Theories must be tested
- Sometimes they are wrong & must be
modified or discarded
EX: The Earth is flat.
Progression of Ideas in Science
• Scientific Law- a statement of
what happens in a certain event
based on verified observations &
experiments
Progression of Ideas in Science
- Explains what happens & not why
- Summaries of the results of many,
many experiments & observations
- When results of a series of experiments
are the same each time they no longer
need to be tested
EX: Newton’s Law of Gravity
Progression of Ideas in Science
• Which one is most likely to be
wrong- hypothesis, theory, or
law?
1.
2.
3.
Hypothesis
Theory
Law
Scientific Method Vocabulary
• Observation- the act of observing
(touch, taste, smell, feel, see, etc.)
• Inference- a quick conclusion that
attempts to explain an observation
• Prediction- to forecast; to guess the
outcome of a situation beforehand
• Analysis- to separate or break apart
into smaller sections for study
Scientific Method Vocabulary
• Conclusion- to close or bring to an
end; to accept or reject a hypothesis
in an experiment
• Data- recorded observations or
measurements
• Hypothesis- a tentative explanation
that accounts for a set of facts & that
can be tested by further investigation
Scientific Method Vocabulary
• Theory- an explanation of a large
body of information, experimental
and inferential, and serves as an
overarching framework for numerous
concepts. It is subject to change as
new evidence becomes available.
• Law- a basic scientific theory that is
no longer tested & is generally
accepted as true (Newton’s Law of
Gravity)
Scientific Method Vocabulary
• Controlled Experiment- an
experiment in which all variables
except the ONE being tested are
identical in order to make the
experiment fair & the results reliable
• Variable- any factor in an
experiment that could affect the
results & is therefore tested
separately
Scientific Method Vocabulary
• Controlled Variable- a variable that
is not changed
• Independent Variable – a variable
that you purposely manipulate
(manipulated variable)
• Dependent Variable- the variable
being observed that changes in
response to the independent
variable (responding variable)
Scientific Method Vocabulary
• Quantitative Data- data that
involves numbers or measurement
usually in the form of a chart or
graph
• Qualitative Data- anecdotal or
descriptive data that does NOT
involve numbers or measurement
The Scientific Method
• An organized way to solve a
problem through experimentation &
observation.
The 6 Steps of the Scientific Method
1. State the Problem
• Form a question about a specific
event or reaction
EX: Mouthwash kills bacteria.
Which brand works best?
2. Collect Information
• Research the problem
EX: Read the labels of 3
common brands of mouthwash
and see which has the most
antiseptic (germ-killing)
ingredients.
3. Form a hypothesis
• Make an educated guess based on
your research.
A hypothesis can be recognized
by an “if, then” statement.
EX: If Listerine has more antiseptic
ingredients than Scope or Wal-Mart brand,
then it will kill more bacteria.
4. Design an Experiment
• Devise a way to test your hypothesis.
Create a CONTROLLED experiment.
• A controlled experiment MUST have
2 groups.
CONTROL GROUP: all
conditions remain the same
EXPERIMENTAL GROUP: only
the condition that you are
testing for is changed
ONLY 1 condition is changed!
• Establish the variables for your
experiment.
INDEPENDENT VARIABLE: the
variable that is changed, manipulated
(X axis for graphing)
DEPENDENT VARIABLE: the
change caused by the manipulation
of the independent variable
(Y axis for graphing)
Mouthwash Experiment
Control Group
-no mouthwash
Petri dish
Bacteria grown
from swab
Listerine
Experimental
Group
Scope
Wal-Mart
brand
Mouthwash Experiment
INDEPENDENT VARIABLE:
Type of Mouthwash
DEPENDENT VARIABLE:
Amount of bacteria killed
5. Collect & Analyze Data
• Run the experiment & document the
data
• 2 Types of Data
QUANTITATIVE: numerical data,
deals with specific quantities, usually
in the form of a graph or chart
QUALITATIVE: descriptive data,
describes how something looks,
smells, sounds, or feels; deals with
qualities
QUALITATIVE EX: The control group and
the Wal-Mart brand have a strong smell;
the Listerine & Scope don’t smell as bad.
QUANITATIVE EX:
Area of Inhibition for Mouthwash Brands
5 min
10 min
15 min
20 min
Control
Listerine Scope
Wal-Mart
0 mm
0 mm
0 mm
0 mm
3 mm
4 mm
6 mm
8 mm
1 mm
3 mm
4 mm
4 mm
2 mm
3 mm
5 mm
6 mm
6. Draw Conclusions
• Determine from the data collected if
the hypothesis was correct or
incorrect
EX: Listerine did kill more bacteria
than the other brands because it had
more antiseptic ingredients.