Question → Hypothesis → Procedure → Results → Conclusion → Share
Process of Scientific Inquiry
- Make an observation
- Identify a problem or question
- Formulate a hypothesis (relationship between IV and DV)
- Make a prediction
- Design the experiment
- Gather results
- Interpret results and form conclusions
- Share findings (written and verbal)
Components of a Scientific Experiment
- Independent Variable (IV): variable being changed by researcher
- Dependent Variable (DV): variable being measured by researcher
- Standardized Variable: variables that remain constant during the experiment
- Control: group that does not have an independent variable
Types of Graphs
- Line graph: Changes over time
- Bar graph: Comparable values
- Pie graph: Show percentages of a whole
- Scatter graph: High SD is bad, shows that results are unreliable
All graphs need a title and a caption.
Research Design
- Title: The Effect of _____ on _____
- Research Question: How does ____ affect ____?
- Hypothesis: If ____, then ______
- Prediction: If the hypothesis is correct, then ______.
Scientific
Inquiry and Experimental Design: Part 1 – Introduction to the Process
Scientific investigation
is a methodical, logical process that begins with the senses. Humans use our
senses to investigate the natural world all the time. It’s a matter of survival.
Scientists use instruments to augment their senses. They follow a sequential
set of steps designed to lead to an objective investigation of questions about
the world around us – the scientific method. You know the steps (see Figure 1). It all begins with observation. Some great
scientific discoveries in science have been made using meticulous observation
and inductive and deductive reasoning. This is called discovery-based
inquiry. Most scientific investigations
are hypothesis-driven. In this type of inquiry, observations lead to a question
and a hypothesis that is ultimately tested using an experiment. This process
requires creativity. Researchers have to design their procedure. Before
gathering any materials or recording any data, they spend countless hours
scouring the literature to learn what other scientists have discovered about
the question in prior research projects. The researcher uses this information
to develop his/her hypothesis, which is not a guess at all, but a
well-researched proposed solution to the research question. Scientific
hypotheses are based on scientific evidence and are falsifiable. Next, the
researcher designs an experiment to test the hypothesis. Sometimes this
requires building new instruments. For example, early doctors did not have
x-ray machines. Using the scientific method, scientists have accumulated a body
of knowledge based on factual evidence and have made discoveries that
significantly improve the lives of us all.
The process of scientific
inquiry is a powerful tool investigational tool, but it has limitations. Doing
scientific research requires looking into a black box, because when we do
research, unless we are double-checking previous conclusions, we do not know
the answer to the question. Just as we cannot look into a black box, scientists
cannot ever be 100% certain about their findings. We use statistics to determine our accuracy.
Despite the limitation, though, many scientific findings have withstood the
test of time, repeated testing, and rapidly increasing technology. We live in a
very technical world that relies heavily on scientific discoveries. A basic
understanding of science is imperative in today’s world. That understanding
begins with the process that is used to do science: the process of scientific
inquiry. In today’s lab, you will practice doing science.
Figure 1: The process of scientific inquiry.
o
Identify
and characterize questions that can be answered through scientific
investigation.
·
Practice: Which of these questions can be
answered scientifically?
A) Are
serial killers evil by nature?
B) What
is the cause of AIDS?
C) Why
is the grass green?
D) What
is the best recipe for chocolate chip cookies?
E) Does
watching television cause children to have a shorter attention span?
Questions B, C,
and E can be answered through scientific investigation.
o
Define
hypothesis and explain what characterizes a good scientific hypothesis.
·
Hypothesis – well-researched proposed
solution to the scientific question
o
The scientific method applies only to
hypotheses that can be proven false through experimentation
o
The hypothesis must clearly state the
relationship between the dependent and independent variable.
·
Examples-
o
Not valid: More people behave immorally
when there is a full moon than at any other time of the month.
o
Plants absorb water through their leaves
as well as through their roots.
·
Practice: Which of the following would be
a useful scientific hypothesis? Why?
A) Mice require calcium for developing strong
bones.
B) The
higher the intelligence of an animal, the more easily it can be domesticated.
C) An
active volcano can be prevented from erupting by throwing a virgin into it
during each full moon.
Question A
would be a useful hypothesis, because it can be measured using instruments.
Question B is invalid because it would be difficult to measure the intelligence
of an animal, and Question C is invalid because it has no basis of scientific
theory and would be inhumane to test.
o
Identify
and describe the variables of a scientific experiment.
·
Independent variable: the variable being
changed
·
Dependent Variable: the variable being
measured
Practice
experimental design:
IV:
Type of fertilizer
DV:
Amount of corn growth
Control:
Treatment group with no fertilizer added
Standardized
Variables: Amount of water, location of corn crop, species
of corn crop, soil plants are growing in, amount of sunlight exposed to
Number of plants per group: At
least 3
Further investigation: How does the amount
of fertilizer affect corn growth? How does the amount of water affect corn
growth?
Scientific
Inquiry and Experimental Design: Part 2- Investigating Cardiovascular Fitness
Overview of Experimental Design
An experiment must be well- planned to obtain robust
results that can lead to sound conclusions. The process begins with a focused
question that can be answered scientifically. For example, questions such as
“Does chocolate make people happy?” cannot be answered scientifically since
happiness is a subjective human emotion and cannot be measured. However, one
could investigate the question “Does eating chocolate stimulate the release of
serotonin (a calming neurotransmitter)?” This leads to a hypothesis that can be
tested using an experiment. For example: Eating chocolate stimulates the
release of serotonin. Two groups of subjects could be established. Participants
in the treatment group would eat chocolate; participants in the control group
would not eat chocolate. Serotonin levels would be measured and a mean value
calculated for each group. By the way, the results of such experiments support
the hypothesis. Eating chocolate does result in increased serotonin levels.
Now let’s consider a different hypothesis: Light
affects plant growth. To test this hypothesis, you could establish several
groups of plants and expose them to different amounts of sunlight each day and
measure their growth over time. The experimental design would only be valid if
you started out with plants of the same species, age, size and general health
and all other conditions were the same (soil type, water, etc.) Variables that are maintained constant are
called standardized variables. If
standardized variables are not kept constant, it is impossible to be certain if
the difference in growth (dependent
variable) resulted from light (the independent
variable) or from the other factors.
The group of plants left in the lowest light exposure group would be the
control group. Notice that it is not always possible to eliminate the
independent variable completely as is the case in this experiment.
Practice: Bold the dependent variable, underline the
independent variable and identify some standardized variables for the example
below.
Chlorophyll
a levels will increase as levels of dissolved nitrogen
increase in lakes, ponds, streams and estuaries.
Standardized variables include type of water
(fresh), time of year sample is taken, geographical area.
Scientific
Inquiry and Experimental Design: Part 2- Design and Experimentation
Learning
Outcomes:
1. To
design an experimental procedure to answer a scientific question.
2. To
use the scientific method of inquiry to investigate a research question.
3. To
gather experimental data and graphically analyze it.
4. To
formulate and report scientific conclusions.
Introduction:
In this exercise, you will work together with your
classmates to practice investigating a scientific question using the scientific
process. This process begins with identifying a question that can be
investigated using the scientific method of inquiry and culminates with a
conclusion based on critical analysis of the data collected during an
experiment designed specifically to investigate the question and to test its
proposed solution, the hypothesis.
Question:
Cardiovascular
fitness can be determined by measuring a person’s pulse and respiration rate
before and after a given time of aerobic exercise. A person who is more fit
will typically have a relatively slower pulse rate and a lower respiratory rate
after exercise, and his/her pulse rate should return to resting rate more
quickly than that of a person who is less physically fit. Your assignment is to
investigate the effect of a well-defined, measurable, controllable independent
variable on cardiovascular fitness.
Discuss
several specific questions that you
can ask about an independent variable related to the broad topic of cardiovascular fitness. List your questions in your
lab notebook. For example, your question might be “Does cigarette smoking have
an effect on cardiovascular fitness?”
·
Does the use of birth
control affect cardiovascular health?
·
Does the amount of sleep
a person gets affect cardiovascular health?
·
Does the amount of red
meat a person eats affect cardiovascular health?
·
Does stress affect
cardiovascular health?
Choose
your best question and propose a testable hypothesis. Contribute your question
and hypothesis to the class list. Record the question and hypothesis selected
by the class in your lab notebook.
Hypothesis
If birth control medication is taken, then cardiovascular health
will be worse.
Materials
Platform
Clock
with a second hand
Metronome
The Experiment
If
you were performing an independent investigation, at this time you would read
relevant scientific article or texts to determine an accepted procedure used by
scientists to test cardiovascular fitness. You would discover that there is a
test, called the step test, that is used for this purpose (Kusinitz and Fine,
1987). Here are the basic elements of this test:
1.
The
subject steps up and down on a low platform, approximately 8 in. from the
ground, for three minutes at a rate of 30 steps per minute. (Using a metronome
to count steps ensures that all subjects maintain a constant step rate.) The
subject should step up and then step down again, keeping the rate constant.
2.
The
subject’s pulse rate is measured before the test and immediately following the
test. The subject should be sitting quietly when the pulse is counted. Use
three fingers to find the pulse in the radial artery (the artery in the wrist,
above the thumb). Count the number of beats per minute. (Count the beats for 30
seconds and multiply by 2.)
3.
Additionally,
the pulse rate is measured at 1-minute intervals after the test until the pulse
rate returns to normal (recovery time). Count the pulse for 30 seconds, rest 30
seconds, count 30 seconds, and rest 30 seconds. Repeat this procedure until the
pulse returns to normal. Record the
number of minutes to return to the resting pulse rate. (Do not record the
pulse rate.)
Record the
following information in your lab notebook.
●Components of
Your Experiment:
Independent
variable: The usage of birth control medication
Standardized
variables: Temperature of room of test subjects,
equipment type, time exercised
Control:
Individuals who do not use birth control
Level of
treatment: Group who uses birth control
Replication:
None
●Summarize the experiment designed by your
class.
In this experiment, the effects of the use of birth control
medication on cardiovascular health will be tested using the recovery time of
13 test subjects in an introductory general biology laboratory class.
●Prediction
If the hypothesis is true, then subjects who use birth control will
have a higher recovery time than students who do not use birth control.
●Procedure
Study participants will be selected based on the study
variables. Participants will use the Harvard Step Test (Kusinitz and Fine,
1987) to evaluate cardiovascular fitness.
Results
Table
1: Results of Step Test (Pulse rates are beats per minute)
Before
step test
Resting
Pulse Rate
|
72
|
After
step test
Active
Pulse Rate
|
105
|
Recovery
time (min)
|
1
|
Mini Lab Report
Title: The Effect of the Usage of Birth Control Medication on
Cardiovascular Fitness
Research Question: Does the use of birth control affect cardiovascular health?
Hypothesis:
If birth control medication is taken, then
cardiovascular health will be worse.
Prediction:
If the hypothesis is true, then subjects who use birth
control will have a higher recovery time than students who do not use birth
control.
Procedure: Thirteen subjects evaluated their resting heart beat for one
minute and recorded it. Each one then stepped on and off a platform
approximately 8 inches off the ground at a rate of 30 steps per minute for 3
minutes. Immediately following the activity, they evaluated their active heart
beat for one minute. Simultaneously, the student measured how long it took for
their active heart rate to return to their resting heart rate. The results were
recorded into the lab notebook.
Independent variable(s): The
use of birth control medication
Dependent variable(s): Recovery
time
Standardized
variables: Temperature of room of test subjects,
equipment type, time exercised
Control: Subject who do not
take birth control.
Results:
Table 1: Recovery time
(minutes) and survey responses recorded for a class of 13 college students in
an introductory biology lab course.
Recovery Time
(minutes)
|
% Body
Fat
|
BMI
|
Stretch
Group
(Y/N)
|
Hrs of Sleep/ Night
|
Birth
Control
(Y/N)
|
Exercise
3.5 hr a wk (Y/N)
|
Cardio
(Y/N)
|
Weights
(Y/N)
|
|
1
|
1
|
19%
|
28.2
|
N
|
8
|
N
|
Y
|
N
|
Y
|
2
|
0
|
29.2%
|
27.4
|
N
|
6
|
Y
|
Y
|
Y
|
Y
|
3
|
0
|
24%
|
21.8
|
N
|
8
|
N
|
Y
|
Y
|
Y
|
4
|
0
|
31.9%
|
27.9
|
N
|
8
|
N
|
Y
|
Y
|
Y
|
5
|
1
|
34%
|
28.6
|
N
|
6
|
N
|
N
|
||
6
|
0
|
22%
|
21.7
|
N
|
8
|
N
|
Y
|
Y
|
Y
|
7
|
1
|
19.3%
|
19.4
|
N
|
7
|
Y
|
N
|
||
8
|
1
|
27.5%
|
23.5
|
N
|
8
|
Y
|
Y
|
N
|
Y
|
9
|
3
|
28.4%
|
26.5
|
Y
|
7
|
Y
|
Y
|
Y
|
Y
|
10
|
3
|
Y
|
8
|
Y
|
Y
|
Y
|
N
|
||
11
|
3
|
Y
|
6
|
N
|
Y
|
N
|
Y
|
||
12
|
3
|
Y
|
7
|
N
|
Y
|
Y
|
Y
|
The subjects highlighted in yellow are
included in the treatment group. The subjects highlighted in blue are included in the control
group.
Figure 1: Class results
Conclusion: The results of this experiment supported the hypothesis.
Comparison with other research revealed similar trends. Future experiments
could be improved by increasing the sample size and standardizing more
variables.
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