FACTS: A Forensics Approach to the Chemistry Teaching of Students.
Personal Reflections:
The three weeks we taught the forensics unit were the shortest three weeks of the year. Not only
did the students enjoy the unit, we all learned something new every day. The highlights of our
experiences with this unit are:
 Students have 2 or more opportunities to practice a skill
 Relevant to students lives
 Uses chemistry concepts in a real-world situation
 Captures the interest of all students in chemistry class
 Technology is used as a tool.
 100% of students were actively engaged for three full weeks
Abstract:
FACTS creatively integrated a series of investigative, high interest, hands-on forensic lab
activities into a chemistry curriculum in order to help students better understand, apply and master
chemistry concepts. Lab activities emphasized the use of scientific inquiry as a way of thinking and
problem solving while relating scientific processes to technological and societal issues. FACTS featured
the identification of unknowns as cooperative teams of students learned chemistry techniques employed
in forensic science such as the classification of fingerprints, spectrophotometric and chromatographic
analysis of over-the-counter drugs, inks and plastics, DNA fingerprinting, and using physical and
chemical properties to identify white powders, different soils, plastics, and simulated body fluids.
Technology was included in the collection and analysis of forensic evidence and was used to encourage
students to creatively explore beyond the basic lesson. The activities repeatedly reinforced the National
and the North Carolina Science Standards. After completing the series of structured activities, mastery of
chemistry concepts was assessed by having students play the role of forensic detectives using the
chemistry skills and forensic techniques they had learned to collect, analyze and interpret evidence found
at a crime scene.
Education Objectives or Outcomes Desired:
The student will
 Learn and apply basic chemistry concepts
 Understand the nature of science
 Develop and practice science process skills
 Incorporate technology as a tool for collecting and analyzing data
 Demonstrate good lab practices
 See how chemistry relates to their lives in an authentic way
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FACTS --- McCluskey and Halpin
Assessment tools: Students turned in a reporting sheet for each lab activity for daily assessment. The
summative assessment was an open-ended application of what students have learned by actually solving a
crime scene. Student’s grades were determined by their report which included diagrams of the crime
scene, strategic plan for investigation, list of evidence with truth table, daily log of the teams activities,
results of all laboratory experiments, and a one page summary of evidence used to determine the guilty
suspect.
Types of Activities: Investigative, high-interest, hands-on lab activities were used to help students
understand, apply and master basic chemistry concepts. After completing the nine labs, students
demonstrated their understanding of the chemistry concepts by solving a crime scene. Forensics teams
analyzed and evaluated evidence collected at a crime scene from which they build a logical case to
implicate one of several suspects.
The National Science Standards were used as the foundation for the creation of FACTS. The
developers of this unit believe that:
"…the Standards describe a vision of the scientifically literate person and present criteria
for science education that will allow that vision to become reality. Why is science
literacy import? First, an understanding of science offers personal fulfillment and
excitement -- benefits that should be shared by everyone. Second, Americans are
confronted increasingly with questions in their lives that require scientific information
and scientific ways of thinking for informed decision making. And the collective
judgement of our people will determine how we manage shared resources -- such as air,
water, and national forests."
(Science Standards page 11)
We looked for a unit that would excite students to pursue investigations that were relevant in their lives.
The decision to develop a forensics unit was in part due to two cases in the news which were getting a lot
of press and for which all students had an opinion, many of which were not based on analyzing the
evidence.
The North Carolina Standards Program Goals serve as the more specific framework for this forensics unit
in chemistry. They are design to: (1) develop an understanding of the nature of science (2) develop the
ability to use process skills, (3) develop the ability to use science manipulative skills, (4) develop a
positive attitudes toward science, (5) Understanding the relevance of current topics in chemistry, (6)
understanding properties of solutions (7) understanding of regularities in chemistry (8) Understanding of
changes in chemistry (9) understanding of models in chemistry. These goals are broken down into more
specific objectives and coded by a number (see Table 1). In the section that follows Table 1, reference
numbers are used to identify the specific objective. Each lab is described in brief.
Making Observations and Drawing Conclusions Based on Data Analysis of White
Powder –Day one
Description/Objective: In this lab students learned to identify white powder by their chemical and
physical properties. The five common white powders used were aspirin, sugar, Bufferin, flour, and baking
soda. After successfully identifying the known powders, students were given an unknown.
Materials: wellplates, toothpicks or stirring rods, droppers, white powders: aspirin, powdered sugar,
flour, buffered aspirin, baking soda, distilled water, universal indicator, 0.1M HCl, 0.1M Fe(NO3)3, iodine
solution
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FACTS --- McCluskey and Halpin
Finger Printing –Day Two
Description/Objective: Students learned to identify the three main patterns of fingerprints. They then
took their fingerprints and classified them according to the type. Students also learned to lift fingerprints
from various types of materials. Students were assessed by their ability to identify an unknown print by
comparing it to five known prints.
Materials: inkpads, tape, fingerprint cards
Paper Chromatography – Day Three
Description/Objective: Students were introduced to the concept of paper chromatography as a means for
separation a mixture of two or more components due to their difference in solubility, charge, and/or
molecular size. Students identified an unknown ink sample based on the data they collected in the lab.
Materials: filter paper, scissors, 250 mL beakers, water, an assortment of pens with ink that is water
soluble.
Toxicology using chromatography – Day Four
Description/Objective: Students analyzed simulated body fluids to determine the cause of death due to
ingestion of a toxic substance. Tests were conducted to determine the presence of mercury, lead, aspirin
overdose, or diabetes. After conducting tests on known substances students tested and identified an
unknown sample.
Materials: chromatography paper, developing chamber, pencils, rulers, stapler, hair dryer, plastic wrap,
hot plates, beakers, chemicals: glycine, methionine, Benedict’s solution, ninhydrin, aspirin, 0.1M FeCl2,
water, developing solution: n-butanol, water, glacial acetic acid
Drug Analysis using TLC chromatography paper –Day Five
Description/Objective: Students learned to conduct thin layer chromatography and calculate Rf values of
known compounds. The known values are used to identify over- the-counter drugs such as Advil, Aleve,
BC powder, Excedrin, and Goody’s Powder. EWHS students sent samples to NCSSM students for
analyses using an infrared spectrophotometer. NCSSM students then e-mailed results to the EWHS
students.
Materials: developing tanks, silica gel think-layer plates with fluorescent coating, pencils, UV light,
rulers, capillary tubes, acetaminophen, aspirin, caffeine, ibuprofen, naproxen, salicylamide, Advil®,
Aleve®, BC powder®, Excedrin Extra Strength®, Goody’s powder®, 95% ethanol denatured.
Blood Analysis – Day Six
Description/Objective: There are many substances that make a stain similar to dried blood. In this
activity students tested substances for traces of the heme group found in blood. False positive results
were discussed. Students were cautioned not to base conclusions on one test alone.
Materials: filter paper, animal blood, droppers, solution #1, solution #2, solution #3
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FACTS --- McCluskey and Halpin
Plastics Identification – Day Seven and Eight
Description/Objective: Students identified recyclable plastics using relative density, rigidity, appearance,
flammability, drips when melted, smoke color, and Bilstein test. Students were then given an unknown
piece of plastic to identify. EWHS students sent samples to NCSSM students for analyses using an
infrared spectrophotometer. NCSSM students then e-mailed the results to the EWHS students.
Materials: plastic samples recycle code 1-6, forceps, burners, insulated copper wire, matches, aluminum
foil tongs,glycerol, ethylene glycol, 91% stock commercial isopropanol
stock isopropanol/water solutions (mL/mL): 20/80, 30/70, 40/60, 50/50, 60/40, 65/35
Soil Analysis – Day Nine
Description/Objective: In this activity students identified soil samples using general appearance, density
gradient, settling rates, pH, and chemical and physical properties. After conducting the experiments using
known soil samples they were given an unknown sample to identify. Student used electronic probes
interfaced with the calculator to measure pH, conductivity, and settling rate. Students downloaded their
data from the calculator to a computer for data analysis and printing.
Materials: soil samples A, B, C, density gradient tubes – corn oil, water, glycerol, corn syrup
CBLs, pH probes, conductivity probes, colorimetry probes, TI-82 calculators, magnifying lens, UV light,
well plates, beakers, distilled water, 0.1 M HCl,
DNA Fingerprinting – Day Ten
Description/Objective: . In this activity students learned the chemistry concepts related to the DNA
extraction from cells. They learn biotechnology techniques of using gel electrophorus to identify DNA
fingerprints. These data are compared to the DNA from known individuals.
Materials:
gel chambers, power supplies, micro-pipettes, PCR kits (Carolina Biological Supply), agarose
Day Eleven -- Crime Scene observations and sketching
At the beginning of this period students entered a room where a crime scene had been staged.
Students were divided into teams of 4-5. In these teams each student selected a role as a criminal
investigator based on their expertise or interest (see description of roles in Supported
Documents). Each team was given time to inspect the scene, sketch a diagram, and study
photographs. They then worked in their teams to design a plan for collecting and analyzing data.
The evidence at the crime scene includes materials that can be identified by the nine labs
described above. Students determined which data to collect, what experiment to conduct, and
how to analyze that data.
During the following four days students worked to complete their plan of data collecting,
experimentation, data analysis, concluding, and write their report.
Day Twelve -- Collecting and Analyzing Data
Day Thirteen -- Collecting and Analyzing Data
Day Fourteen -- Drawing Conclusions based on Data
Day Fifteen -- Presenting findings to a Judge asking for Court Order for Arrest
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FACTS --- McCluskey and Halpin
Documentation presented to the judge must include the following:
Each team must turn in each of the following:
1. Detailed diagram of the crime scene - due when crime is solved
2. Brief strategic plan for investigation -due at beginning of day 2
3. List of evidence -- use attached truth table -- due when crime is solved
4. Daily log of teams activities-- due when crime is solved
5. Results of all laboratory experiments conducted-- due when crime is solved
6. One page summary listing guilty party and evidence used to reach that conclusion
--due when crime is solved
Criminal Investigation
Team Assignment
Detective Chief--
serves as team leader as well as investigator, divides the tasks
among the team members and checks to make sure all
examinations and reports are completed.
Field Investigator #1 -- serves as the recorder to document all evidence, complete
documents to be filed with the district attorney’s office.
Field Investigator #2 -- serves as the leader in the laboratory investigations, obtains all
the equipment of experiments to be conducted on the evidence.
Field Investigator #3-- serves as evidence investigator, checks out information from the
evidence locker.
Field Investigator #4 -- serves as special detective as assigned by the Chief Detective.
Task
Chief Detective
Field Investigator #1
Field Investigator #2
Field Investigator #3
Field Investigator #4
Name
Evidence – Truth Table
In the table below, list the facts that you observe either from the crime scene, experiments you
conduct, or evidence obtained from the evidence box. For each piece of evidence check the
person(s) incriminated by this observation.
Fact
Suspect
#1
#2
#3
#4
Person
#5
teacher unknown
(add more lines)
Based on the evidence listed above we would like to issue a warrant for the
arrest of ________________________________ suspect #____.
To District Attorney:
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FACTS --- McCluskey and Halpin
TYPE OR PRINT ALL INFORMATION IN BLACK
FIRST NAME MIDDLE NAME
LEAVE BLANK
LAST NAME NAM
CONTRIBUTOR
ALIASES
STATE USAGE
FBI LEAVE BLANK
DATE OF BIRTH DOB
MONTH DAY YEAR
SIGNATURE OF PERSON FINGERPRINTED
THIS DATA MAY BE COMPUTERIZED IN LOCAL
STATE AND NATIONAL FILES
SIGNATURE OF PERSON TAKING
PRINTS
DATE
NCO92013Y
CITY-CO BOF I
RALEIGH, NC
DATE ARRESTED OR
RECEIVED DOA
YOUR NUMBER, OCA
SEX
RAC
E
PLACE OF BIRTH POB
HGT
WGT
EYES
HAIR
LEAVE BLANK
CLASS _______________________________________
CHARGE
FBI NO. FBI
REF.
SID NO. SID
_______________________________________
NCIC CLASS-FPC
SOCIAL SECURITY NO.
SOC
FINAL DISPOSITION
IF ARREST FINGERPRINTS SENT FBI PREVIOUSLY AND FBI NO.
UNKNOWN, FURNISH ARREST NO. ________________ AND
DATE _______________
STATUE CITATION CIT
1.
2.
PALM PRINTS TAKEN YES _________
NO __________
PHOTO AVAILABLE
NO __________
YES _________
3.
ARREST DISPOSITIONS AND
RESIDENCE OF PERSON FINGERPRINTED
EMPLOYER: IF U.S. GOVERNMENT INDICATE SPECIFIC AGENCY
SCARS, MARKS, TATTOOS AND AMPUTATIONS, SMT
IF MILITARY, LIST BRANCH OF SERVICE AND SERIAL NO.
OCCUPATION
BASIS FOR CAUTION ICO
DATE OF OFFENSE DOO
REPLY DESIRED? YES _______
NO ________
MISC. NO MNU
IMMEDIATE REPLY DESIRED? YES _______
NO ________
WILL ACCEPT COLLECT CALL OR WIRE? YES _____ NO ______
TELEPHONE OR WIRE NUMBER: ____________________________
SKIN TONE SKN
SEND COPY TO NAME, ORI NUMBER AND ADDRESS:
1. R. THUMB
1. L. THUMB
6
2. R. INDEX
3. R. MIDDLE
4. R. RING
5. R. LITTLE
2. L. INDEX
3. L. MIDDLE
4. L. RING
5. L LITTLE
FACTS --- McCluskey and Halpin
Bibliography
1.
Allen, Sarah, Chemistry teacher, North Carolina School of Science and Mathematics, Durham,
NC, 27705 (Plastics Lab)
2.
“Blood Markers”. ChemMatters, April 1992 Page 4, American Chemical Society, Washington, DC
3.
“DNA Fingerprinting”. ChemMatters, October 1991, American Chemical Society, Washington, NC
4.
Evident Crime Scene Products, Rt. #1, Box 265G, Union Hall, VA 24176-9635
5.
“Fingerprint Discovery Kit”, Marty Ludas, Forsenic Press, 1400 Lakepark Dr., Raleigh, NC 27612
6.
“Forensics Chemistry”, Version 2.0 Chemsource – SourceBook Module, Funded by NSF Grant
number TPE 88-50632.
7.
Lytle, LT, Hedgecock DG (1978) Chemiluminescence in the visulation of Forensics bloodstains. J
for Science 32: 550-562
8.
MacKenzie, Norma, Providence Country Day School, Charlotte, NC (idea for soils & household
products)
9.
“The Casebook of Forensics Detection-How Science Solved 100 of the World’s Most Baffling
Crimes” Colin Evans, John Wiley & Sons, Inc., Professional, Reference and Trade Group, 605
Third Ave., New York, NY 10158-0012
10.
Timmer, William, “An Experiment in Forensic”. Chemistry Journal of Chemical Education,
Volume 63, Number 10, October 1986, page 897-898
11.
Website – http://forsenicfiles.bc.sympatico.ca/
12.
Website – http://www.webmasters.net/gde/micscope.htm/
13.
Website – http://www.pbs.org/wgbh/frontline/salvi/salvihearing/salvihearing3.html/
14.
Website – http://www.pbs.org/ktca/newtons/9/mrdrmysr.html/
Laboratory Activities
Do to the page limits of this publication we are able to provide only one of the lab activities. If you would like
copies of the other labs you may download them from the web site
- paradigm.ncssm.edu .
In our classes we conducted the labs listed above. You may elect to do a subset of the activities
and also add your own labs. Our physical science teachers conducted a forensics unit using only
the white powder , finger printing, paper chromatography, and plastics identification labs. They
then used two days to have students investigate their crime scene.
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FACTS --- McCluskey and Halpin
Forensics Science -- Lab #1
When a crime has been committed it is the responsibility of the police, FBI, ATF, or sheriff to
collect evidence in order to solve the crime. The evidence must be collected and analyzed
properly to hold up in a court of law. In this unit you must collect data and draw conclusions
from that data. A forensics scientist can use hunches and intuition in trying to solve a crime,
however, when it comes to going to court, only actual facts should be presented. An expert
witness may make inferences but they are subject to question by the defense.
Observation: a statement of fact based on what you see, hear, taste, touch, or smell. A good
investigator takes careful notes of every thing at the scene. Sketches and photographs are
important parts of every investigation and are completed prior to touching or collecting any
evidence.
Types of Observations
1. Physical properties of a substance are those characteristics that can be observed such
as color, odor, smell, density, melting point, boiling point, hardness, conductivity, or
taste.
2. Chemical properties of a substance are those characteristics that describe how the
substance reacts with other chemicals.
Conclusion: a statement of fact based on the results of experimental testing. For example, if
you have a white powder and add iodine solution to the powder and it turns black, you can
conclude that the white powder contains starch.
Inference: a judgment or opinion based on observations and/or conclusions from testing. It is a
fact that some illegal drugs are mixed with flour. If a white powder tests positive for starch, one
could infer that the powder is an illegal drug mixed with flour. This inference would not stand up
in court. A good investigator might infer that the powder was an illegal drug but should order
additional testing to confirm the actual composition of the powder.
Objectives:
Make observations
Draw conclusions
Make inference
Solve for an unknown
Identify common substance which are over-the-counter drugs or compounds often used in
the cutting or making of illegal drugs
The FBI Crime Lab works very closely with the pharmaceutical companies to produce tests for
all new drugs as they are developed. Tests are developed to identify very small samples of a drug
and files to serve as reference are kept for forensics investigations to use.
Drug identification is very important. If you arrive on the scene and find an unconscious victim
who has injected some drug, you need to identify the substance as quickly as possible. Some
over-the-counter drugs may cause poisoning and/or death especially in children. In this activity
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FACTS --- McCluskey and Halpin
you will test for common over-the-counter drugs as well as common substances which are found
in illegal drugs.
Aspirin, Acetyl salicylic acid: a small sample or a solution of aspirin can be identified by
adding a solution of ferric nitrate. The solution will turn brownish purple if aspirin is present.
In addition to the acetyl salicylic acid (active ingredient) aspirin tablets also contains starch,
silicon dioxide, and preservatives. A solution of aspirin should be acidic.
Bufferin (buffered aspirin): you should get the same results with this sample as you did for
regular aspirin. In addition you may get a fizzing produced when you add HCl. This is because
some aspirins are buffered by a carbonate.
Baking Soda, Sodium Hydrogen Carbonate: a sample or a solution of baking soda can be
identified by adding a solution of HCl acid. When the acid is added the solution will fizz.
Baking soda is used in the making of crack cocaine. A solution of baking soda should be basic.
Tylenol:
Flour: a carbohydrate of high molecular weight composed of numerous glucose units.
Sugar: sucrose is common table sugar and is made of a glucose and a fructose unit.
Procedure:
1. Add a small sample of each white powder in 4 of the wells as labeled below. Record your
observations in the chart.
aspirin
sugar
bufferin
flour
Tylenol
baking
soda
Iodine
Fe(NO3)3
HCl
water
universal
indicator
2. Add 5 drops of water to each sample in the first well. Describe what happens.
3. Add 1 drop of universal indicator to each of the wells containing your sample and water. In
the Data Table, write the color the solution turns.
4. Add 5 drops of HCl to each sample in the second well for all six samples. If a chemical
reactions occurs you should see a gas being former and the solution fizzes. In the Data Table
write FIZZ if you see a reaction taking place.
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FACTS --- McCluskey and Halpin
5. Add 5 drops of Fe(NO3) solution to each sample in the third well for all six samples. If a
chemical reactions occurs you should see a brownish purple product produced. In the Data Table
put a “P” in each circle where you see this reaction occur.
6. Add 5 drops of iodine solution to each sample in the last well for all six samples. If starch is
present the solution will turn black. Write a “B” in the Data Table if the solution turns black.
7. Obtain an unknown sample from the evidence box. The sample is one of the six substances
you have just tested. Identify the sample.
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FACTS --- McCluskey and Halpin
Name_______________________________
Data Table
1. Record your observations in the table below.
aspirin
sugar
bufferin
flour
Tylenol
baking
soda
Iodine
Fe(NO3)3
HCl
water
universal
indicator
2. Describe what happened when you added water to the sample.
a. aspirin + water____________________________________________________
__________________________________________________________________
b. sugar + water ____________________________________________________
_________________________________________________________________
c. bufferin + water __________________________________________________
_________________________________________________________________
d.flour + water _____________________________________________________
_________________________________________________________________
e.tylenol + water ___________________________________________________
_________________________________________________________________
f. baking soda + water _______________________________________________
_________________________________________________________________
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FACTS --- McCluskey and Halpin
3.
Unknown sample # _________
Describe the physical appearance of the sample:___________________________
__________________________________________________________________
Test conducted
Results
Sample # _______ is ___________________. Evidence to support my conclusion is
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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FACTS --- McCluskey and Halpin