Scientific Method
Course
Forensic Science
Unit I
Understanding the
Scientific Method
Essential
Question
How are the
basics of science
used in forensics?
TEKS
§130.295(c)
(2)(A–E)
Prior Student
Learning
Lab Safety
Estimated Time
5 hours total
 1 hr. lecture
 3 hrs. activities
 1 hr. quizzes
and exam
Rationale
Forensics is an actual application of science and technology to solve crimes
in the criminal justice system. Since forensics employs a vast number of
scientific fields, knowing the strengths and limitations of scientific theories
and hypotheses, and understanding the scientific method is crucial to using
science to its full potential in the pursuit of justice.
Objectives
The student will be able to:
1. Define science and the scientific method.
2. Differentiate between scientific hypotheses and scientific theories.
3. Explain how the scientific method is used to answer questions and
solve cases in forensics.
4. Use the scientific method to solve an investigation, including all the
steps of the method and an experiment.
Engage
Show students an episode of the television show that illustrates the scientific
method. Ask the students to try and find the steps of the scientific method
using the Find the Scientific Method Handout, and discuss their results as a
class. Use the Find the Scientific Method Teacher’s Notes to guide the
discussion, and use the Discussion Rubric for assessment.
Key Points
I. Science – modern science tries to understand and explain how the
natural world works now and how it got to be that way
A. Facts about science
1. The study of natural phenomena
2. Studies what can be observed, measured, and tested by
scientific methods
3. We must use our senses to observe and evaluate
4. Based on the assumption that the universe is orderly,
reasonable, and testable
5. Used to predict natural events that may occur
6. Based on physical, mathematical, and conceptual models
7. Classified into many different fields, topics, or categories for
specialized study
8. The different fields overlap and depend on each other for further
knowledge and explanations
9. A vast body of knowledge that is always changing and
expanding, but is does have limitations
10. Objective, unbiased, and impartial—or it should be
B. Myths about science
1. A rigid collection of facts that are inflexible
2. Able to explain the answer to every question (some phenomena
are not scientifically testable)
3. Unorganized, unrelated, or untestable
4. Based on that which cannot be observed or measured, or that
which is outside of our senses to be perceived
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5. Only based on one disciple, field, or topic of knowledge
6. Subjective, biased, or partial (it should not be)
C. Scientific Explanations – Hypothesis, Theory, or Law
1. Hypothesis – an educated guess based on observation
a) Can be given as an explanation for the occurrence of an
event or a presumption to guide an investigation
b) Should be based on some knowledge or research
c) Must try to answer a scientific question
d) Must be testable by known scientific methods
e) Can be supported or refuted through further observation or
experimentation
f) Can be proven wrong; it doesn’t have to be right
(1) A wrong hypothesis only leads to another hypothesis
(2) A better product, a better clue, a better suspect
g) Should be stated in such a way that the experiment will
collect measureable/quantifiable data if possible
2. Theory – summarizes a hypothesis or group of hypotheses that
have been supported with repeated testing over a wide variety
of conditions over time
a) Are valid as long as no evidence disputes them
b) Are well-established and highly reliable
c) Can be used as principles of explanation and prediction for
a group of phenomena
d) Can be disproven, modified, or changed with new scientific
knowledge, observations, and technology
3. Law – generalizes a body of observations that can be used to
describe or predict something universally understood in nature
a) At the time that it is made, no exceptions can have ever
been found in a law
b) Laws never explain “why” something happens, only that it
will always happen the same way with no exceptions
c) Example – Newton’s Law of Gravity could be used to
predict the behavior of a dropped object, but it could not
explain why it happened
d) Theories explain “why” something happens; laws predict
that it will always happen the same way
D. Six Criteria of Science: CONPTT
1. Consistent – results are based on repeatable observations
and/or explanations
2. Observable – limited to the basic human senses or extensions
of the senses (microscopes, computers, etc.)
3. Natural – a natural cause must be used to explain why or how;
supernatural explanations are not allowed
4. Predictable – the result or observation can be used to make
predictions about natural events
5. Testable – the natural cause of the event must be testable
through the process of science and/or controlled experiments
6. Tentative – theories are subject to revision and correction, even
to the point that the entire theory might be proven wrong
E. Non-Science – an area of science that does not meet the criteria of
science or CONPTT
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1. Such areas may be very logical and based on good reasoning,
but do not fall into the true realm of science
2. Examples: a belief system (religious), philosophy, personal
opinion, ethic, or sense of aesthetics
II. Scientific Method – the established method of research and discovery. It
follows an eight-step process to collect and evaluate information, and
maintain objectivity when arriving at the conclusion. It is used to solve
every case in the criminal justice system
A. General Steps of the Scientific Method
1. Asking or defining a question – start with a question that can be
tested
a) The question should be specific
b) It can be based on observations
c) Information is normally gathered before the final question
is decided
2. Researching the question or problem – books, journal articles,
manuals, magazines, newspapers, the internet, etc. are used in
the research
a) The hypothesis may have been already studied or
researched (there may already be an answer)
b) Research sources used should be scientific, objective, and
unbiased
3. Forming a hypothesis – the answer to the question is given in
the form of an educated guess of what is expected to happen or
the answer
a) The hypothesis must be in the form of a statement
b) The hypothesis must be researched before it’s stated (that
is why it is an educated guess)
c) The hypothesis must be testable; if it is not, it is not a valid
hypothesis
d) The hypothesis must allow for a variable to be tested and
what results are expected
e) Should be given in this format: “If this________ is
done/changed, then this_______ will happen/be observed”
f) Null hypothesis – what the researcher is seeking to not
have happen, to disprove, or to nullify (sometimes given in
addition to the hypothesis)
(1) The opposite of the hypothesis
4. Developing and performing the experiment
a) Must test the hypothesis
b) Should have planned steps for implementation
c) Should only have one variable that is tested
d) Either supports or disproves the hypothesis
e) The experiment will be retested to validate the results
5. Collecting the data – a lab notebook is kept through all of the
steps of the scientific method
a) All observations that led to the question should be
recorded, as should the research that was done, the
formation of the hypothesis, and any hypotheses that were
not used
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b) Write down how the experiment was designed and all its
steps
c) All the details, data, and measurements of the experiment
are documented
(1) Document every detail
(2) Write down any mistakes or changes
(3) Leave nothing out
d) Clearly labeled tables are normally used to document data,
especially changes over time (this makes graphing data
easier later)
6. Analyzing the data – data collected is scrutinized
a) Information is compared and contrasted
b) Graphs, tables, and charts are used to visually review the
data
c) Averages, means, and deviations should be calculated;
statistical analyses should also be performed
7. Writing the conclusion – data/results are studied to draw
conclusions
a) It is stated whether the results support or disprove the
hypothesis (it is perfectly okay for the hypothesis to be
incorrect)
b) Any additional data found, or new results established that
were unexpected, might need research to be explained
c) All problems or sources of error should be discussed
d) Results should be interpreted without any bias or
prejudice, and as objectively as possible
e) Any future data or experiments that are needed for further
information should be considered
f) The results gathered should be repeatable by others
8. Communicating the results – the results are communicated and
published in written format in a scientific journal
a) Lecturing, sharing, and retesting are performed
b) The format used for communicating depends on the
actually topic studied and the type of audience who will be
reviewing/using the scientific research
B. Scientific Method Intersections
1. There are many crossovers, turnarounds, and repeats in the
scientific method; it is seldom that the method proceeds through
all eight steps in an organized fashion
2. This is especially true in criminal investigations: research yields
more knowledge that changes the hypothesis and the
experiment (investigation), more data is collected that also
might change the hypothesis, the exploration changes, results
are not expected, conclusions can change, and the process
may begin again
C. Experiments
1. Experimental design – the experiment should be well-designed
and meet certain criteria
a) The experiment should be based on the research that was
done in forming the question and the hypothesis
b) All steps and conditions for the experiment should be
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planned and detailed
c) Steps should be recorded before the experiment, and a
record made of any changes made during or after the
experiment
d) The experiment should be designed, carried out, and
recorded in such a way that further investigators can
repeat the procedure (and hopefully get the same results)
e) All variables should be organized and managed
f) Technology use should be planned
g) Data collection should be done with extreme care and
answer the following questions
(1) How will data be collected?
(2) Will data collection be reliable?
(3) How can data be measured, and quantitative and
objective?
(4) Is data subject to bias in any step?
(5) Will data collection be precise and accurate?
h) The method of recording data collection should also be
premeditated
i) The experiment should be planned so that the hypothesis
made is tested and the original question is answered
j) The experiment should be conducted several times before
results are published and communicated
2. Variable – anything that can be changed or controlled in an
experiment, and/or any changes that occur because of
something else that changed
a) Three types of variables
(1) Independent variable
(a) The one factor that is changed, or the one factor
that is different between the groups
(b) One factor is best, so you can depend on your
results, but in analyzing a criminal case all of the
variables cannot always be controlled or
minimized
(2) Dependent variable
(a) The variable that is observed to see whether it is
affected by the independent variable
(b) This is normally the data that is collected as the
experiment progresses
(c) The dependent variable depends on what was
changed in the experiment, or it depends on the
independent variable
(3) Controlled variables (often called constants or
controls)
(a) Things that could change in the experiment, but
should be kept constant or unchanging
(b) If these change you have more than one
independent variable and your data collected or
results may not be valid
b) Example – in an experiment comparing the fizz released
from different types of soda your variables are
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(1) Independent variable – the type of sodas tested (this
should be the only difference between the sodas)
(2) Dependent variable – the amount of fizz released
(3) Controlled variables
(a) Same size/type of soda cans
(b) Bought at the same store, with the same
expiration dates
(c) Kept at the same temperature, with the same
amount of agitation per can
(d) The same method of measuring fizz volume
should be used
III. Contribution of Science
A. Science and the scientific method are an integral part of mankind and
have been for many years
B. Explaining the natural world around us is a quest that many share
C. The scientific method is our way of consistently answering questions
and creating new inspiration
D. Scientific ideas have limitations and can evolve over time, but
scientific knowledge is the most reliable knowledge we have about
the natural world
E. The criminal justice system has been tremendously impacted by the
use of the scientific method and scientific knowledge, and science is
the basis of the field of Forensics
Activities
1. Choosing the Right Equipment. Have the students select tool(s) for the
hypothesis on the Choosing the Right Equipment Worksheet. Have
students discuss their answers as a class. Use the Choosing the Right
Equipment Worksheet Key and/or the Discussion Rubric for assessment.
2. Bikini Bottom Experiments. Have the students complete some simple
experiments. The experiments and answer keys at
http://sciencespot.net/Media/scimthdexps.pdf may be used.
3. Designing Experiments. Have the students read the scenario and answer
the questions on the Designing Experiments Handout. Use the Designing
Experiments Key for assessment.
4. Purchase Power. Have the students select an everyday product and test
it with their own experiment using the Purchase Power Handout as a
guide. Use the Purchase Power Checklist for assessment.
Assessments
Scientific Method Exam
Scientific Method Quiz
Choosing the Right Equipment Worksheet Key
Purchase Power Checklist
Scientific Method Crossword Puzzle Key
Discussion Rubric
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Presentation Rubric
Research Rubric
Materials
Scientific Method computer-based presentation
Choosing the Right Equipment Worksheet and Key
Designing Experiments Handout and Key
Purchase Power Handout and Checklist
Scientific Method Crossword Puzzle and Key
Expanding to Real Life Handout
Laser projector
Computer
Worksheets
Computer Lab or Internet Sources
Resources
Saferstein, Richard. Forensic Science: An Introduction. New Jersey:
Pearson Prentice Hall, 2008.
Bertino, Anthony J. Forensic Science: Fundamentals & Investigations.
Mason, OH: South-Western Cengage Learning, 2009.
Deslich, Barbara; Funkhouse, John. Forensic Science for High School
Dubuque, Iowa: Kendall/Hunt Publishing Company, 2006.
http://sciencespot.net/Media/scimthdexps.pdf
Accommodations for Learning Differences
For reinforcement, have students practice vocabulary by completing the
Scientific Method Crossword Puzzle. Use the Scientific Method Crossword
Puzzle Key for assessment.
For enrichment, have students research, summarize, and present an article
related to science. Use the Expanding to Real Life Handout for the activity,
and the Research Rubric and Presentation Rubric for assessment.
State Education Standards
Texas Essential Knowledge and Skills for Career and Technical Education
§130.295. Forensic Science (One Credit).
(2)
The student uses scientific methods and equipment during
laboratory and field investigations. The student is expected to:
(A)
know the definition of science and understand that it has
limitations, as specified in subsection (b)(2) of this
section;
(B)
know that scientific hypotheses are tentative and
testable statements that must be capable of being
supported or not supported by observational evidence.
Hypotheses of durable explanatory power which have
been tested over a wide variety of conditions are
incorporated into theories;
(C)
know scientific theories are based on natural and
physical phenomena and are capable of being tested by
multiple independent researchers. Unlike hypotheses,
scientific theories are well-established and highly7
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(D)
(E)
reliable explanations, but they may be subject to change
as new areas of science and new technologies are
developed;
distinguish between scientific hypotheses and scientific
theories;
plan and implement descriptive, comparative, and
experimental investigations, including asking questions,
formulating testable hypotheses, and selecting
equipment and technology;
College and Career Readiness Standards
I. Nature of Science: Scientific Ways of Learning and Thinking
A. Cognitive skills in science
1. Utilize skepticism, logic, and professional ethics in science.
B. Scientific inquiry
1. Design and conduct scientific investigations in which hypotheses
are formulated and tested.
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Name________________________________
Date______________________
Scientific Method Exam
Multiple Choice
_____1. The first step in the scientific method is
a. Making observations
b. Conducting experiments
c. Analyzing data
d. Defining the problem/asking the question
_____2. To gather information, we can
a. Read books
b. Ask questions
c. Use our senses to study things
d. All of the above
_____3. When we make an educated guess we are forming
a. Data
b. A hypothesis
c. Variables
d. A factor
_____4. Our recorded observations are called
a. Data
b. Control factors
c. Hypotheses
d. Experiments
_____5. At the end of the scientific method, we must state a
a. Purpose
b. Question
c. Hypothesis
d. Conclusion
_____6. Every experiment must have only one
a. Variable
b. Step
c. Measurement
d. Object
True or False (T or F)
_____7. The first step of the scientific process is testing the hypothesis.
_____8. Sometimes, steps of the scientific process must be repeated.
_____9. Every experiment should have at least three experimental factors or variables.
_____10. A control group is a factor that is missing the variable, but is the same as other factors
in every other way.
_____11. Written observations made while using the scientific process are known as data.
_____12. A theory is a hypothesis that has not yet been tested.
_____13. Measurements must be made carefully to make sure all factors, except the variable,
are the same.
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Scientific Method Exam Key
1. D
2. D
3. B
4. A
5. D
6. A
7. F
8. T
9. F
10. T
11. T
12. F
13. T
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Name________________________________
Date______________________
Scientific Method Quiz
Matching
1. ____ An educated guess
A. Scientific Method
2. ____ Factor in an experiment that is missing the variable but
is the same as other factors in every other way
B. Single Variable
3. ____ Written or recorded observations made while using the
scientific method
4. ____ Step-by-step process that scientists have developed to
help them solve problems and test new ideas
5. ____ A hypothesis that has been tested many times and is
supported by data
C. Control
D. Hypothesis
E. Experiment
F. Data
G. Theory
6. ____ Factor being tested; the one factor that is different from
all others in an experiment
H. Conclusion
7. ____ An activity or group of activities performed to test a
hypothesis
8. ____ Final statement made after an experiment to prove or
disprove the hypothesis
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Fill-in-the-blank: Read the following paragraph, and circle the word that best fills each blank.
The ___9___ method is a process that scientists use to help them test new ideas. The first step
in the process is defining the ___10___ . Next, information must be gathered using one of more
of the five ___11___ . The scientist then makes an educated guess or a ___12___ . This is
tested by performing one or more activities called ___13___ . Observations are made and
recorded. The recorded observations are known as ___14___ . After analyzing the data, the
scientist comes to a ___15___ that either proves or disproves the hypothesis. When a
hypothesis is tested many times and supported, it becomes known as a___16___.
9.
13.
A. Variable
B. Scientific
C. Control
D. Biological
A. Theories
B. Experiments
C. Properties
D. None of the above
10.
14.
A. Conclusion
B. Data
C. Experiment
D. Problem/question
11.
A. Data
B. Hypotheses
C. Structures
D. Expressions
15.
A. Senses
B. Controls
C. Solutions
D. Solvents
12.
A. Meeting
B. Consideration
C. Laboratory
D. Conclusion
16.
A. Variable
B. Factor
C. Hypothesis
D. Consideration
A. Solvent
B. Control
C. Deduction
D. Theory
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Scientific Method Quiz Key
1. D
2. C
3. F
4. A
5. G
6. B
7. E
8. H
9. B
10. D
11. A
12. C
13. B
14. A
15. D
16. D
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Name________________________________
Date______________________
Scientific Method Crossword Puzzle
Across
1. Anything that can be changed or controlled in an experiment, and/or any changes that occur because of
something that did change
3. The study of natural phenomena
4. An educated guess based on observation
6. The first step of the scientific method is to have one of these
8. Results are based on repeatable observations and/or explanations
10. Scientists use their data to make charts and what to communicate the results of an experiment?
13. Theories are subject to revision and correction, even to the point of the entire theory being proven wrong
14. Can be used as principles of explanation and prediction for a group of phenomenon
Down
2. After scientists make a hypothesis, they perform what to collect data?
5. Scientists write this after an experiment to summarize it and its results
7. The natural cause of the event must be
9. This kind of variable is the part of the experiment that is affected by the independent variable
11. Is the part of an experiment that is not being tested and is used for comparison
12. At the time that it is made, no exceptions have ever been found to this
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Scientific Method Crossword Puzzle Key
Across
1. Variable – anything that can be changed or controlled in an experiment, and/or any changes
that occur because of something that did change
3. Science – the study of natural phenomena
4. Hypothesis – an educated guess, based on observation
6. Question – the first step of the scientific method is to have one of these
8. Consistent – results are based on repeatable observations and/or explanations
10. Graphs – scientists use their data to make charts and what to communicate the results of an
experiment
13. Tentative – theories are subject to revision and correction, even to the point of the entire
theory being proven wrong
14. Theory – can be used as principles of explanation and prediction for a group of
phenomenon
Down
2. Experiment – after the scientist makes a hypothesis, they perform a what to collect data
5. Conclusion – scientists write this after an experiment to summarize it and its results
7. Testable – the natural cause of the event must be
9. Dependent – this kind of variable is the part of the experiment that is affected by the
independent variable
11. Control – is the part of an experiment that is not being tested and is used for comparison
12. Law – at the time that it is made, no exceptions have ever been found in this
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Name________________________________
Date______________________
Choosing the Right Equipment Worksheet
Directions: The tools we use in science are very important. They don’t have to be complicated
machines or lab equipment. Consider each hypothesis below and write the tool or tools you
could use to prove each hypothesis?
1. It’s warmer on the west side of my house than on the east side.
2. Plants in the sun grow faster than plants in the shade.
3. Taking a shower is quicker than taking a bath.
4. My bedroom is longer than it is wide.
5. I weigh more in the morning than I do at night.
6. I use more milk on my cereal than my brother does.
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Choosing the Right Equipment Worksheet Key
1.
2.
3.
4.
5.
6.
Thermometer
Ruler, calendar
Stopwatch or clock
Tape measure
Scale
Measuring cup
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Name________________________________
Date______________________
Designing Experiments
Directions: Discussing the Scientific Method is one thing; applying it and designing an
experiment is much more intricate and requires complex thinking skills. Use the skills you have
learned to analyze the following situation and answer the questions.
When cells grow uncontrollably and spread to the surrounding tissues, it is called cancer.
Cancer can occur in any living organism, and if the growth of the cells continues, death can
occur. Many cancers can be cured if detected and treated before the rapid spread into
surrounding tissues occurs. Cancers are being studied extensively because of their impact on
human beings. Many studies are done on mice because of the social and ethical implications of
treating humans with cancer as lab subjects.
Suppose a scientist who has been studying cancer cells finds a chemical compound that might
reduce the number of cancer cells. The scientist calls the compound Reduction, and plans a
series of tests to see if the compound reduces the number of cancer cells in mice.
There were 10 mice in the small laboratory and all 10 mice have cancer. The 10 mice were
divided into 2 groups of 5 each. Group A received injections of Reduction. Group B received
injections of a sugar solution. The injections were given every 8 hours for 10 days.
Before beginning the injections, the number of cancer cells in a sample from each mouse was
determined and recorded. After beginning the injections, the number of cancer cells in a sample
from each mouse was determined and recorded every 2 days. If there was a reduction in the
number of cancer cells, Reduction was working. If there was an increase in the number of
cancer cells, Reduction was not working.
Specimen
A3
A5
B2
B3
Table with Some of the Data Collected from Some Mice
Number of Cancer Cells
Beginning
Day 2
Day 4
Day 6
Day 8
Day 10
1000
1050
1050
1075
1100
1000
500
600
650
725
800
825
1500
1520
1530
1550
1600
1625
1200
1225
1250
1260
1275
1290
1. What was the scientist’s hypothesis?
2. What was the control group? the experimental group?
3. What was the independent variable? What was the dependent variable? (be specific for
both)
4. Give all examples of what the controlled variables (constants or controls) should have been.
5. Did Reduction reduce the number of cancer cells in mice? Explain.
6. Was the scientist’s hypothesis correct? Explain.
7. What could the scientist have done to make his results more valid?
8. Should the scientist report this on the experiment and the conclusion he made? Why or why
not?
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Directions: For each of the following scenarios design an experiment. List the question,
hypothesis, experimental procedure, materials, technology required, independent variable,
dependent variable, constants/controlled variable. Also discuss the method of data collection,
technology/equipment needed, units of data to be recorded, and how often the data should be
collected.
A. A veterinarian wants to determine if dogs of the same breed are healthier eating a store
brand, a premium brand, or table scraps. Health is determined by weight and energy levels.
B. A forensic scientist wants to determine the best light to use for finding trace evidence on
carpet. His department has always used regular flashlights, but the latest research suggests
that a Forensic light source (with many wavelengths of light --including ultraviolet, white, and
infrared light) is much better at finding trace evidence.
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Designing Experiments Key
1. That the compound, Reduction, would decrease the number of cancer cells in mice.
2. The control group was group B that received sugar solution. The experimental group was
group A that received Reduction.
3. Independent variable: the Reduction given; Dependent variable: the number of cancer cells
4. -Between both groups everything should be exactly the same except for the chemical given
-Mice of the same age, size, sex, breed, and general health
-Mice all kept in the same room, same type of cage, and same number of mice in each cage
-Cages all kept in the same conditions at the same temperatures
-Mice all fed the same food, and the same amount at the same time
-Mice all given the same volume of injection (just the type of injection is different), same
place on their body, and at the same time of day
-The method of counting the number of cancer cells should be the same in both groups
-The starting number of cancer cells should be almost the same
5. Students should look at the data table to answer questions. In looking at this partial data it
would appear the Reduction did not work. None of the mice had a reduction in cancer cells,
and there was no difference between the tested and untested groups.
6. The scientist’s hypothesis was not correct; none of the mice showed a reduction in cancer
cells between the two groups.
7. More mice should have been used in both groups. A study is much more valid if numerous
subjects are tested. Also, more than one test should be conducted—several repeats are
required, whether the results were what he wanted or not. There may have been a problem
or potential source of error with the mice in these groups. Maybe Group A didn’t get enough
food or had a stronger version of the cancer and that is why the medicine didn’t work.
Repeat testing would hopefully catch any problems.
8. Yes, after he conducts the repeated experiments. Even if his hypothesis was incorrect, it
adds to the scientific knowledge base. Maybe another scientist was planning to test the
same drug and doesn’t need to; maybe testing needs to be done with a higher dose or a
different version of the drug; maybe the drug would work better in another species of animal.
Every result and conclusion has significance.
A. Question: Which type of dog food is the healthiest for a dog?
Hypothesis: If the premium brand is healthier for dogs, when compared to a store brand and
table scraps, then dogs eating the premium brand will gain more weight and have higher
energy levels
Independent Variable: Type of dog food
Dependent Variable: Weight gained and amount of activity
Controlled Variables:
 Dogs of the same breed, sex, age, and general health
 An equal number of dogs in the 3 groups
 Dogs fed the same amount of food, just not the same type of food
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 Dogs fed by the same person, in same size dish, at the same times of day, and with the
same amount of water available
 Dogs kept in the same environment (same yard) at the same temperature, shade, etc.
 The weight of the dogs should be gathered with the same scale (units), by the same
person at the same time of day
 The determination of energy levels should be done with a numerical value, by the same
person, at the same time(s) of day or continually throughout the day/night
Materials:
 60 dogs of the same breed and approximate age, weight, and sex
 3 fenced separate areas for feeding
 Ample supplies of all 3 dog foods (and a measuring device for each food source)
 Dishes of equal size for all dogs
 A measuring cup for each food source
 A metric (Kg) scale for gathering dog weight
 A large yard or area for dogs to have unlimited activity; the yard should be similar in all
areas with equal availability of shade, grass, etc.
 A video camera and source for watching video (monitor, TV, etc)
 A table and materials to record data
Experimental Procedure:
1. 60 dogs will be broken into 3 groups of 20 dogs each
2. Group A will be fed the premium brand, Group B will be fed the store brand, and Group
C will be fed table scraps
3. All groups will be fed 2 cups of food twice a day, and provided with unlimited water
4. All dogs will be weighed in kilograms every morning
5. All groups will be video-taped continuously for 4 weeks. The videos will be analyzed for
time spent sleeping/napping, time spent lying down, standing, walking, running,
barking. All activity will be documented
6. All dogs, foods, environments, and methods of data collection will be monitored and
controlled
B. Question: Which type light source is the best to use in finding trace evidence?
Hypothesis: If the Forensic light source is superior for finding evidence, when compared to a
regular white light, then more trace evidence will be found with the Forensic Light source
Independent Variable: Type of light source
Dependent Variable: Number of particulates of trace evidence
Controlled Variables:
 Light operated by the same person, with the same methods/angles of light
 Same amount, size, and color of trace evidence (hair and fibers) distributed
 Same sources of trace evidence
 Same type and area dimensions of carpet searched
 Same search pattern used
 Same method for collecting evidence
 Same method for counting evidence
Materials:
 4 Forensic light sources
 4 regular white light sources
 Batteries of the same brand for all light sources (if needed)
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Copyright © Texas Education Agency 2011. All rights reserved
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8 rooms of the same size/same area of carpet (10' x 10' at least)
Same carpet covering with the same color (beige) for all rooms
80 pieces of white cotton fibers
80 pieces of dark cotton fibers
80 blond hairs of about 2cm each
80 black hairs of about 2cm each
Search grid for the room sizes
2 technicians to operate light sources and collect evidence
2 evidence distributors
Coveralls (“bunny suits”) for technicians/distributers
Paper for bindle collection
Envelopes or bags for bindles
Tweezers
Trace Evidence Vacuum
4 Magnifying glasses
Experimental Procedure:
1. All light sources will be powered up or new batteries will be used
2. Evidence distributors will be assigned rooms with repeating patterns (each one will get
2 rooms for the white light source, and 2 rooms for the Forensic light source)
3. Evidence will be distributed with a particular and documented pattern in each assigned
room
4. Evidence collectors will be assigned rooms with the same method as the distributors—
so that each collector will have 2 rooms where they will use white light, and 2 rooms
where they will use the Forensic Light
5. The evidence collector will work each room with the same methods of evidence
location and collection, following the same grid plan
6. Evidence will be collected and marked by room and light source
7. A 2-hour interval will be allowed for each room
8. After the room has been searched, the trace vacuum will pick up any evidence left
9. Evidence will be counted and documented from each room (light source/technician)
10. Trace evidence will be catalogued according to color, size, etc.
11. Analyze the type of evidence (and color) and the number found for each light source
22
Copyright © Texas Education Agency 2011. All rights reserved
Expanding to Real Life
Background:
There are many stories in newspapers, magazines and online about people who are using the
scientific method to learn about the world and about how law enforcement is using the scientific
method to solve crimes. Examples include doctors who are trying to cure diseases,
environmentalists who are trying to preserve the earth’s resources, astronomers who are trying
to answer questions about the universe and investigators that have solved cold cases or high
profile situations.
Directions:
Locate an article related to science that you can use to answer the following question: How is
the scientific method involved in the pursuit of knowledge or in the solving of the criminal case?
Present a summary of your article to the class. Your presentation should
1. Discuss every step of the scientific method and how it corresponds to how the
investigator/scientist is making new discoveries or has solved the case.
2. Explain your own thoughts on the importance of the information and what scientific
theories/hypothesis or new technology was used.
3. Meet the minimum and do not exceed the maximum time requirements created by your
instructor.
Assessment:
The Research Rubric and the Presentation Rubric will be used for assessment.
23
Copyright © Texas Education Agency 2011. All rights reserved
Name________________________________
Date______________________
Purchase Power
Part A: Select Your Product:
(1) What product(s) will you test?
(2) (a) What do you want to find out?
(b) Write a question:
(3) (a) What do you think will happen?
(b) Write your hypothesis:
Part B: Plan Your Experiment:
(4) What will you do to ensure reliable results?
(5) What safety issues do you need to address?
(6) What steps will you use in your experiment? Be specific!
MATERIALS NEEDED:
Make a list of the materials you will need for your experiment and indicate the person
responsible for providing the item(s). Check them off as you collect them.
ITEM
PERSON
CHECK WHEN BROUGHT
24
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Part C: Collecting Data: Use the space below to create a data chart to record the information
gathered during your experiment.
Part D: Graphs:
Use the space below, or graph paper, and the data from Part A to construct a graph that
illustrates the results of your experiment.
Use the space below to write a conclusion that summarizes the results of your experiment.
25
Copyright © Texas Education Agency 2011. All rights reserved
Name________________________________
Date______________________
Purchase Power Checklist
Objectives (0 not met, 1 met, 2 exceeded)
Part A: Decide Your Product
Identifies the product(s) to be tested
0
1
2
Question is clearly stated and addresses the topic
0
1
2
Hypothesis is clearly stated and addresses the topic
0
1
2
Materials list is complete
0
1
2
Provides procedures to ensure reliable results
0
1
2
Safety issues are addressed
0
1
2
Follows procedure
0
1
2
Experiment is outlined in easy-to-follow steps
0
1
2
Steps provide good detail
0
1
2
Steps incorporate methods for reliable results
0
1
2
Data is displayed in an organized chart and labeled
0
1
2
Provides a sufficient amount of data
0
1
2
Graph displays results of the experiment
0
1
2
Graph is easy-to-read and labeled correctly
0
1
2
Conclusion addresses results of the experiment
0
1
2
Conclusion addresses the hypothesis
0
1
2
Conclusion is well-written and detailed
0
1
2
Team members worked well together
0
1
2
Team used class time wisely
0
1
2
Team met project deadlines
0
1
2
Part B: Plan Your Experiment
Part C: Collecting Data
Part D: Graphs
Overall Points
Total Points (40 pts. possible)
Comments:
26
Copyright © Texas Education Agency 2011. All rights reserved
Name_______________________________________
Date_______________________________
Discussion Rubric
Objectives
4 pts.
Excellent
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Participates in group discussion
Encourages others to join the
conversation
Keeps the discussion progressing
to achieve goals
Shares thoughts actively while
offering helpful recommendations to
others
Gives credit to others for their ideas
Respects the opinions of others
Involves others by asking questions
or requesting input
Expresses thoughts and ideas
clearly and effectively
Total Points (32 pts.)
Comments:
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Copyright © Texas Education Agency 2011. All rights reserved
Name:____________________________________
Date:_____________________________
Presentation Rubric
4 pts.
Excellent
Objectives
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Topic/Content
 Topic discussed completely and in-depth
 Includes properly cited sources (if used)
Creativity/Neatness
 Integrates a variety of multimedia effects
to create a professional presentation
(transition and graphics) or appropriate
visual aid used
 Title slide, table of contents, bibliography
are included, using acceptable format
Mechanics
 Grammar, spelling, punctuation, and
capitalization are correct
 Image and font size are legible to the
entire audience
Oral Presentation
 Communicates with enthusiasm and eye
contact
 Voice delivery and projection are
dynamic and audible
Audience Interaction
 Presentation holds audience’s attention
and relates a clear message
 Clearly and effectively communicates the
content throughout the presentation
Total Points (20 pts.)
Comments:
28
Copyright © Texas Education Agency 2011. All rights reserved
Name______________________________________
Date_______________________________________
Research Rubric
Objectives
4 pts.
Excellent
3 pts.
Good
2 pts. Needs Some
Improvement
1 pt. Needs Much
Improvement
N/A
Pts.
Question/goal
Student identified and communicated a question
or goal of the research
Research/Gathering information (if relevant)
Student used a variety of methods and sources
to gather information. Student took notes while
gathering information
Conclusion/Summary
Student drew insightful conclusions and
observations from the information gathered.
Information is organized in a logical manner
Communication
Student communicated the information gathered
and summary or conclusions persuasively.
Student demonstrated skill in the use of media
used to communicate the results of research
Reflection
Student reflected on the importance of the
research and its potential application
Total Points (20 pts.)
Comments:
29
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