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Forensic Chemistry

published on: 2/28/2003

Contributing Teacher(s): Stacey Endebrock

Subject Area: Science/Integrated, Science/Physical, Technology Use/Content Specific

Grade Range: High School (9-12)

Materials Needed:

• See each lesson

Objective:

1. The student will use paper chromatography to separate chemicals found in lipstick samples.
2. The student will construct a reference library of lipstick samples and use this library to identify a lipstick found at a crime scene.
3. The student will calculate densities of several glass samples.
4. The student will determine whether two glass samples originated from the same source.
5. The student will organize fiber evidence into a data table and then determine the identity of an unknown fiber.
6. The students will perform tests on soil samples and compare them to the soil test performed on the dirt from a suspect's shoe.
7. The students will perform a series of tests to determine the physical and chemical characteristics of several unknown powders and utilize the test results to identify an unknown substance.
8. The student will gather and analyze evidence from a crime scene to help solve a crime.

Process Standards:

• Goal 1.6 discover and evaluate patterns and relationships in information, ideas and structures
• Goal 1.10 apply acquired information, ideas and skills to different contexts as students, workers, citizen
• Goal 4.1 explain reasoning and identify information used to support decisions

Content Standards:

• Science 1. Properties and principles of matter and energy
• Science 7. Processes of scientific inquiry (such as formulating and testing hypotheses)

  Time Allowance: See each lesson.

  Description: Students will learn a variety of scientific skills that they will organize into a data library and use to help solve a crime.

  Comments: Best taught grades 10-12

  ---

  Classroom Component:

  Implementation:
  This unit may be taught as a whole or the activities may be used individually. There are five preparatory lessons before the "big crime" occurs. The students are to use the skill and knowledge they obtain in the first five lessons to solve the crime at the end of the unit. Each lesson is written so that it may stand on its own. If the teacher wishes to have his/her class perform the final lesson, all previous lessons will need to be performed in order to give the students the background they will need to be successful. Each lesson includes teacher notes and student handouts. Students will need basic knowledge of chemistry. This unit incorporates critical thinking skills, organizational skills and communication skills. This unit allows students to apply science to their lives and teaches them skills they could use in their future careers.
  References:
  Ulmer, Carolyn and Ulmer, Greg "ABC Technologies: Cells and Scientific Instruments" 2000. Ulmer, Carolyn and Ulmer, Greg "ABC Technologies: Forensic Science" 2000. Walker, Pam and Wood, Elaine "Crime Scene Investigations, Real-Life Science Labs" The Center for Applied Research in Education, 1998. This book is loaded with ideas for incorporating all areas of science into forensics.
  Forensics and Glass Chip Density
  Background Information:
  Glass fragments can be used as evidence to help place a suspect at the scene of a crime. Because different kinds of glass have different physical characteristics, types of glass can be distinguished from one another. For example, chips of glass from a broken window may fall into a perpetrator's trouser cuff or shoes. A forensic scientist can identify these chips as part of the broken window. Similarly, parts of a broken headlight found at the scene of a hit-and-run can be used to identify the suspected vehicle. Glass is a hard, brittle substance made of silicon oxides (sand), lime, soda, and oxides of metals. The metal oxides found in most window glass are sodium, calcium, magnesium, and aluminum. Automobile headlights and other heat-resistant types of glass, such as Pyrex, contain boron oxides. Broken glass can be sharp and dangerous. That is why automobile manufactures use tempered and safety glass in vehicles. Tempered glass is made strong by a rapid heating-and-cooling process that introduces stress to the glass surface. When tempered glass breaks, it fragments into small squares that do not have sharp edges. Therefore, tempered glass is not so dangerous as other types of glass. It is used in the side and rear windows of cars and trucks. Windshields are made of laminated or safety glass. This type of glass is strong and break resistant because it is made by sandwiching a layer of plastic between two pieces of ordinary window glass. The forensic scientist uses the physical properties of glass to associate one type of glass fragment with another. One of these physical properties is density. Because different types of glass contain different combinations of metal oxides, they have different densities. Density refers to a material's mass per unit volume, and can be summarized in the formula:

  Density =

  Mass Volume

  The density of a substance remains constant, no matter what the size of the substance. Thus, density of glass can be used to help identify it. A simple three-step method for determining density of a sample is:
• Weigh the sample to find its mass.
• Determine the volume of the sample.
• Divide the mass of the sample by its volume.
Materials:
• An "unknown" glass sample
• 6 glass samples labeled A, B, C, D, E and F. (Caution: sharp glass can easily cut you!!)
• Graduated cylinder
• Scale or Triple-beam balance
• Tweezers
• Water
• Paper Towels
• Calculator
Procedure:
• Place the "unknown" glass sample on a scale and determine its mass in grams. Record this mass on a Data Table that you create to organize your data.
• Remove this sample from the scale. Repeat step 1 with the 6 other pieces of glass.
• Place 20 milliliters of water in the graduated cylinder. Then add the "unknown" glass sample to the water in the graduated cylinder. Read the new volume on the cylinder in milliliters. Take the new volume and subtract 20 to find the volume of the piece of glass. Record this information in your data table.
• Repeat step 3 for the other glass samples.
• Divide the mass of each sample by its volume to determine the sample's density. Record the densities for the glass pieces in your data table.
Postlab Questions (answer the following questions on your own paper using complete sentences!):
• From your experimental results, which of the glass samples (A-F) matched the "unknown"?
• Water has density of 1 g/ml. Based on your work, does glass have a density greater than 1 g/ml or less than 1 g/ml? Explain your answer.
• If you were able to identify the "unknown" glass as the type found at the sight of a hit-and-run accident and were also able to match the "unknown" glass to a suspect's car, does this evidence positively prove that this suspect is guilty? Explain your answer.
• All of the glass samples you tested were not the same size. When determining density, does the size of the sample make a difference? Why or Why not?
Teacher Notes: Forensics and Glass Density
The students will need one class period to complete this activity. You will need 6 types of glass fragments. Sources of glass fragments might include junkyards, glass recycling bins, and auto repair shops. When possible, select glass pieces with rounded edges. Before the lab, decide which glass fragment will be the unknown. You may want to change the unknown each hour if you teach this lesson more than one time during the day. This activity allows for various skill and knowledge levels. I have students working in lab groups. They divide the activities among themselves and monitor each others' results.
Scoring:

Data Table
Table is neat, clearly labeled and all requested information is present:	25
Table is neat, clearly labeled, but missing some requested information:	15
Table is present, not well labeled and missing information:	5
Questions
Questions are answered in complete sentences and are fully explained:	20
Questions are answered in complete sentences but are not all fully supported:	15
Questions are answered in complete sentences but are not supported:	10
Answers are not in complete sentences:	5
Total:	45

WHOSE LIPS TOUCHED THIS? Training Lab—Chromatography of Lipstick
Background Information:
Chromatography is a technique used in labs to separate mixtures of chemicals. There are many kinds of chromatography that can be useful; however, in this lab you will use paper chromatography. In this method, you place the mixture of chemicals to be separated at one end of a strip of paper. This end of the paper strip is then placed in a solvent. The solvent moves up the paper strip; however, as it travels upward it dissolves the mixture of chemicals and pulls them up the paper too. The chemicals in the mixture become separated as the chemicals that dissolve best in the solvent move up the paper strip further than chemicals that do not dissolve as well. So, how does this help solve a crime? Mixing together several different colored chemicals makes colored lipstick. Paper chromatography can separate this mixture of colored chemicals so you can see what colors the lipstick is actually made from. Each makeup company produces their lipstick colors using their own secret mixtures of colored chemicals. This means if you find some lipstick left behind at a crime scene (for instance, on a glass or napkin), you can use paper chromatography to identify what kind of lipstick a person at the crime scene was wearing. This could help you identify a suspect and solve the crime!
• You will be trained to use paper chromatography to separate the chemicals found in lipstick samples.
• You will be trained to construct a reference library of lipstick samples and use this reference library to identify the lipstick left on a napkin.
Materials:
• 6 chromatography paper strips
• 6 different brands of red lipstick
• Acetone (about 10 ml) CAUTION: Be careful! Acetone is flammable.
• Scissors
• 6 test tubes
• Toothpicks
• Beaker
• Test tube rack
• Rulers
• Calculators
Procedure:
• Pick up six test tubes. Use a test tube rack to hold your tubes so they won''t get knocked over.
• Pour about 1 cm of acetone into a test tube. Acetone is the solvent that will move up the paper strip and dissolve the colored chemicals in the lipstick.
• Cut a strip of chromatography paper to form a point on one end.
• Pick up a lipstick to test. Record the Brand and Color of the lipstick being tested on your Reference Library Page. Use the lipstick to make a good-sized dot of color about 1.5 cm up from the pointed end of the paper.
• USE A PENCIL AND MAKE A MARK ON THE PAPER STRIP BESIDE THE INK DOT!
• Lower the pointed end of the paper into the solvent BUT make sure the color dot stays ABOVE the solvent level. Push a toothpick through the top of the paper to hold the strip at just the right level in the test tube.
• The solvent should immediately start moving up the paper strip carrying the lipstick chemicals with it. While waiting for the solvent to rise toward the top of the paper you can set up your other test tubes and test the other lipsticks.
• When the solvent has moved more than half way up the paper strip you can remove the paper from the test tube and immediately MARK WITH A PENCIL THE HIGHEST POINT THE SOLVENT TRAVELED UP THE PAPER STRIP.
• Let the strip dry and then tape it on your Reference Library Page under its correct brand name.
• Continue testing all of the lipsticks. When you are finished, pour the solvent back into its storage container.
CALCULATING Rf VALUES AND DESCRIBING YOUR LIPSTICK SAMPLES
• You have probably noticed that each lipstick uses a different combination of chemicals to produce their lipstick colors. It should be fairly easy for you to test an unknown lipstick sample using chromatography and use your Reference Library to match colors and determine which lipstick was left behind at a crime scene.
• Look closely at each lipstick's chromatography strip and determine how many different chemicals were present in each lipstick sample. Each chemical should appear as a different colored smear on your paper strip; however, some chemicals may be overlapping. Record the Total Number of Colored Chemicals present for each ink sample on your Reference Library Page.
• Look closely at each lipstick's chromatography strip and record the colors that are visible in the order that they appear. Begin with the original ink dot and list the colors as you move up the paper. Each color represents a different chemical present in the lipstick. Record the colors you observe on your Reference Library Page (Colored Chemical #1 = pink color, colored Chemical #2 = orange color, etc.)
• To prove that a lipstick sample is a certain brand and color you will also need to calculate the Rf values of the different colored chemicals present in the lipstick. Rf is a simple calculation that compares the distance the solvent traveled up the paper strip to the distance a chemical traveled up the same strip. First, look at a chromatography strip and measure the distance in millimeters from the original color dot to the final point the solvent traveled. The distance you just measured is the SOLVENT DISTANCE MEASUREMENT. Record this measurement in the correct location on your reference Library Page.
• Next measure, in millimeters, from the original color dot to the highest point the first colored chemical (Colored Chemical #1) traveled up the strip. This is the CHEMICAL DISTANCE MEASUREMENT for Chemical #1. Record this measurement in the correct location for Colored Chemical #1.
• If there is a Colored Chemical #2 present on the strip measure, in millimeters, from the original color dot to the highest point this second colored chemical (Colored Chemical #2) traveled up the strip. This is the CHEMICAL DISTANCE MEASUREMENT Chemical #2. Record this information in the correct location for Colored Chemical #2.
• If there is a Colored Chemical #3 present, repeat the chemical distance measurement for Chemical #3.
• Calculate the Rf value for each colored chemical in your lipstick sample using the simple formula below:

  Rf Value =

  Chemical distance measurement solvent distance measurement

• Record the Rf values for each colored chemical in the ink on your Reference Library Page.
• Repeat these measurements and Rf calculations for each of the lipsticks tested.
• Keep your Reference Library Page so that you can use it to determine what kind of lipstick was left behind at a crime scene. This may be just the evidence you need to solve the case!
Postlab Questions (answer in complete sentences on your own paper):
• In this experiment, what is the purpose of the acetone?
• Do you think water could have been used in place of the acetone? Why or Why not?
• Do you think the discovery of a certain brand of lipstick at a crime scene is enough evidence to link a person with a crime? Why or Why not?
• Did any of the samples of lipsticks have the came chromatography results? If so, which ones?
• What are some other mixtures that you think can be separated by chromatography?
Reference Library for Lipsticks and Their Chemical Colors

Tape Strip Here	Tape Strip Here	Tape Strip Here
Total # of Colored Chemicals ____	Total # of Colored Chemicals ____	Total # of Colored Chemicals ____
Solvent Distance Measured ____	Solvent Distance Measured ____	Solvent Distance Measured ____
Colored Chemical # 4 Color______________ Distance Measured____________ Rf_______________	Colored Chemical # 4 Color______________ Distance Measured____________ Rf_______________	Colored Chemical # 4 Color______________ Distance Measured____________ Rf_______________
Colored Chemical #3 Color_______________ Distance Measured_______________ Rf____________________	Colored Chemical #3 Color_______________ Distance Measured_______________ Rf____________________	Colored Chemical #3 Color_______________ Distance Measured_______________ Rf____________________
Colored Chemical #2 Color_________________ Distance Measured______________ Rf_________________	Colored Chemical #2 Color_________________ Distance Measured______________ Rf_________________	Colored Chemical #2 Color_________________ Distance Measured______________ Rf_________________
Colored Chemical #1 Color_____________ Distance Measured_____________ Rf__________________	Colored Chemical #1 Color_____________ Distance Measured_____________ Rf__________________	Colored Chemical #1 Color_____________ Distance Measured_____________ Rf__________________
Original Ink Dot	Original Ink Dot	Original Ink Dot

Teacher Notes: Lipstick Lab
Use only red lipstick colors. There are many different brands to choose from. You may have students bring in samples for extra credit to save on your science budget. Be sure you personally run a chromatography on each sample and have a reference library of your own to use for scoring and comparisons.
Comments/Time/Modifications:
This lab will take two days to complete. It will take 15 to 20 minutes to complete a "run" as the acetone rises up the paper strip. Try to run them in an undisturbed area of the room. Warm lights, sun and breezes will cause the acetone to evaporate off the paper and the acetone will rise at a slower rate. This is a good lab to set up in groups. You may require one Reference Library per group instead of one for each person. This would allow the students of various talents and abilities to divide themselves up into tasks they may successfully perform. One student may cut the strips and set them up. Another students may take the measurements, and a different student does the calculations on the calculator and records them on the data sheet. Each student should double-check everyone's work to ensure a quality reference library for future use. I do require all the students to answer the questions. I have the students store their Reference Library in the classroom to prevent it from being lost in the future. Make sure you copy enough Reference Library Pages. Each group will need one page for every three lipsticks tested. As a group evaluation I give each lab an "unknown" lipstick and they have to figure out which color and brand of lipstick it is for their assessment grade.
Fibers and Forensics
Background Information:
Fibers, strands of thread that make up yarn, are all around us. You encounter a variety of fibers each day. Fibers make up thousands of products, including clothing, upholstery, carpet, rope, and building components. As you interact with these products, loose fibers become attached to your body and clothes. When you enter a room, you pick up some of the fibers present in the room. You also drop some of the fibers you are carrying. Therefore, fiber evidence can often provide information about where people have been. For fiber evidence to be useful in a crime scene investigation, scientists must be able to narrow down its origin to one or two sources. Because most clothing, upholstery, and carpet are mass-produced, this is sometimes difficult to do. Only under unusual circumstances can a fiber positively identify a person. Fibers can be divided up into two large groups: natural and man-made. The earliest people wore animal skins and furs for clothing. Since the Stone Age, people have been weaving fibers from plants and animals into fabric for clothing. Wool, silk, cotton, flax, and the husks of some dry fruits are examples of natural fibers. From these plant and animal products, people learned to form individual threads that could be woven into large pieces of cloth. By the time of the Industrial Revolution, weaving was a mechanized process that produced plenty of fabric for a growing population and its needs. However, the fabric industry still depended on nature for its raw materials. Drought, flooding, disease, and cold weather could badly damage the fiber crops and reduce the amount a cloth available. After the Industrial Revolution, scientists began searching for a fiber that could be made in the lab. Such a discovery would provide manufacturers with a constant supply of fibers. About 100 years ago, the first man-made, or synthetic, fiber was created in the lab and named "rayon." Rayon was made by chopping and chemically treating wood pulp and cotton to produce a soft mass of cellulose. This cellulose was then forced through tiny openings in a spinneret to form threads. Until the 1970's, more natural than synthetic fibers were used as raw materials to make products. At the present time, however, about twice as much synthetic fiber than natural fiber is used to make fabric. Many types of synthetic fibers have been invented since the appearance of rayon. Man-made fibers are generally classified into the following two groups, depending on whether or not they originated from cellulose:
• Fibers derived from cellulose include rayon and acetate.
• Fibers that are not derived from cellulose include nylon, polyester, acrylic, and spandex.
In this training lab you will collect and analyze different types of fibers and identify an unknown fiber.
Materials:
• Compound light microscope
• Slide
• Cover slip
• Forceps
• White paper
• Candle
• Match
• Blue fibers
• Samples of wool, rayon, silk, polyester, and cotton
Procedure:
• Collect a blue fiber from the "victim" by carefully lifting the fiber with a pair of forceps. Do not touch the fiber with your hands. Place the fiber on a piece of white paper, then fold the paper in half twice.
• Carry the fiber to your lab station. Prepare a wet-mount slide of the fiber by placing it on the slide, adding a drop of water, and covering the fiber and water with a cover slip.
• Examine the fiber under low, medium and high magnification of your microscope. Sketch what you see. Note any pits or striations on the fiber. Place the sketch and notes in your data table.
• Compare this fiber to known samples of wool, rayon, silk, polyester, and cotton. Sketch each of these samples at low, medium and high power. Place your sketch and notes about the fibers in your data table.
• Light your candle and note the burning characteristics of the unknown fiber to the known samples. Record your observations in the data table.
• Holding the fiber in the forceps, bring it close to, but not touching, a flame. Describe the fiber's behavior as it approaches a flame: does it begin to melt, ignite, or curl?
• Holding the fiber in forceps, touch the fiber to a flame. Does it ignite quickly or slowly? Does it sputter, drip, or melt?
• Remove the fiber from the flame and describe how it behaves. Does it self-extinguish, continue to burn, or continue to glow?
• Note any odor associated with the fiber in the flame. Does it smell like vinegar or hair?
• What kind of residue is left after the fiber is removed from the flame? Does the fiber leave a white, fluffy ash, a hard bead, or a melted blob?
Postlab Questions (answer the following questions in complete sentences and on your own paper):
• From your observation of the fibers under the microscope, which type of fiber is most like the unknown fiber taken from the victim? Describe the similarities of these two fibers.
• From the burning tests, which type of fiber is most similar to the unknown fiber taken from the victim? Describe the characteristics they have in common.
• Why might an investigator want to identify unknown fibers from a crime scene?
• What must scientists be able to do in order for fiber evidence to be useful in a crime scene investigation?
• From where do we get the materials to make natural fibers?
• How are man-made fibers classified? Give examples of each type.
• You investigated the properties of five different types of fibers in this lab. What are some other characteristics of these fibers that we could have analyzed? Why would it be important to know the characteristics of these fibers that you just listed?
• Judging from this lab and your own personal experiences describe the types of products made from the five fibers you analyzed. Why would you use that particular fiber for the products(s) you listed? What are the pros and cons of that fiber's use for the product you listed?
Data Table Examination of Fiber Under the Microscope
Type of Fiber Low magnification sketch Medium magnification sketch High magnification sketch Wool Rayon Silk Polyester Cotton Unknown
Data Table Behavior of Fibers in Flame
Approaching FlameIn flameRemoved from flameOdorResidue Wool Rayon Silk Polyester Cotton Unknown
Teacher Notes: Fibers and Forensics
This lab will require two class periods to complete. You will have to collect samples of fabric made of wool, rayon, polyester, silk and cotton. It is important to collect all of the samples in the same color. You may choose whatever fiber you wish to be the one found on the victim. A paper cutout of a victim may be placed on the floor or you can draw an outline of the victim on the floor with chalk. Sprinkle a few of the unknown fibers on the victim. Place samples of wool, cotton, polyester, rayon and silk on a table so that the students can pull sample fibers from them.
Accommodations:
• Some students have a very difficult time explaining in writing what they observe. It would be helpful to model this in front of the class. Strike a match and ask a student(s) what they observed. Write it on the board so they can see the transition from verbal to written language. Ask students to use all their senses: sight, sound, smell, touch and sound.
• Check the students' data tables as the lab is progressing.
• Allow extra time for students to answer the questions.
• Bring in examples of products made from these materials.
• Group students so that there are different learning levels at each lab.
Scoring:

Microscope data table
Detailed drawings and notes in each box	15
Drawings are not detailed and only a few notes	10
Drawings lack detail and no notes	5
Not all boxes contain drawings	0
Flame data table
Detailed observations within each box	30
Notes in each box, some detail	25
Notes in each box, very little detail	15
Data table has some entries but is not complete	5
Answers to Questions
All questions fully answered in complete detail.	40
Questions are answered, but not in complete sentences	30
All questions are attempted, but not fully answered	20
Some questions are attempted	10
Little or no thought given to answers	0
TOTAL:	85 points

Forensics and Unknown Substances Using Standardized Tests to Identify Unknown Substances
Background Information:
The collection of evidence at a crime scene is very important to any criminal investigation. Once this evidence has been collected and packaged properly, it is transported to the crime lab. Crime labs frequently receive unknown substances taken from a crime scene. Experts in the crime lab have the task of determining the physical and chemical identity of these substances. Many times these mysterious substances are illegal drugs. The findings of the crime lab are important in determining the guilt or innocence of a suspect. In the case of determining the identity of an unknown substance, crime lab experts must use testing procedures that give characteristic results. These tests and their results must be established prior to the examination of the unknown substance. Once the tests are verified, they are recorded and used repeatedly to prove the identity of suspect substances. For example, if you want to determine if an unknown white powder is cocaine, you must have a previously established, positive test for cocaine. Then you can conduct this established test on an unknown white powder. It is also important to perform more than one positive test on an unknown. Proper identification requires that you use enough different tests to rule out the possibility that the unknown may be any other substance. For example, a lab technician may be testing an unknown white powder to determine whether or not it is cocaine. To be thorough, this technician will run a series of tests on the powder. If all tests are positive for cocaine, then the technician feels certain that the results are correct. The forensic scientist in the crime lab must carefully perform each test on the unknown. Then the results must be precisely recorded. The results he or she gathers must be so exact that the identification is correct beyond a reasonable doubt.
In this lab:
• You will perform a series of tests to determine the physical and chemical characteristic of several unknown powders.
• You will utilize your test results to identify an unknown substance.
Here is the story (this is a STORY and is not based on any known facts!!!!!!!)
Hillsboro High School has a drug problem. Over the past year, illegal drugs have been seized from student lockers on five occasions. All of these illegal drugs are white powders that look remarkably like table salt. During a recent locker search, investigators collected several zip-lock bags filled with a white powder. Before charges can be pressed on the individual in possession the identity of the powders must be established. You are a member of a forensic science lab team that has been sent to Hillsboro High School. A temporary lab facility has been set up at the high school. The unknown white powders are delivered to you in the lab so you can determine their identity. Due to limitations in equipment at the school, you have been asked to use a simple series of tests to determine the identity of the powders. To enable you to do this, six KNOWN white powders have been provided. You will run tests on each of the six known powders and record your results. Later you will compare results with those from tests of unknown powders collected during locker seizures. Your findings will determine the charges (if any) brought against the students in possession of drugs. A brief overview of the white powders previously discovered at Hillsboro High School includes the following: Escape: a mild hallucinogen. First offense is usually probation. Peppy: a mild stimulant; often results in psychological dependence. First offense results in 6 months to one year in prison. Vavoom: a strong stimulant; causes physical dependence. First offense results in 1 to 3 years in prison. Droop: a moderate depressant; causes physical dependence. First offense results in 1 to 3 years in prison. Bang: a strong narcotic that causes physical and psychological dependence. First offense can result in 5 to 10 years in prison. Table salt: found in a student's locker as a joke.
Materials:
Samples of the six white powders ( A, B, C, D, E, F) in individual zip-lock plastic bags: A: Escape B: Peppy C: Vavoom D: Droop E: Bang F: Table salt Teaspoon Hand lens Black construction paper Aluminum foil Hot plates Labels Lugol's solution Medicine dropper Diluted acetic acid Distilled water 1M sodium carbonate solution 7 test tubes and stoppers Stirring rod Unknown sample in zip-lock bag
Procedure, Part 1: Developing a positive test for the six unknown powders
Obtain a zip-lock bag of each of the six known samples A through F. Record your results for tests conducted on the six known powders in Data Table 1. If nothing happens in a specific test on a known substance, record ND (no data) in the proper location on the data table. At the end of Part A, you should have written in each box on the chart.
• Place a small amount of sample A on the black paper and observe its appearance with a hand lens. Record your results. Repeat this for sample B through F. Dispose of the sample and the paper in the trashcan.
• Place ½ teaspoon of sample A in a test tube. Add 10 drops of vinegar to the test tube. Record your observations. Repeat this test with the remaining five powders. Wash out each test tube.
• Label the six pieces of aluminum foil A, B, C, D, E, and F. Place ½ teaspoon of each of the six samples on the appropriate piece of foil. Place the six squares on a hot plate set at a medium setting. Observe each for several minutes. Record your results. Dispose of the foil and its contents.
• Place ½ teaspoon of sample A in a test tube. Add 10 ml of distilled water. Stopper the test tube and shake for a few seconds. Record your observations. Repeat this for the remaining samples. Do not dispose of the samples. You will use them in the next step.
• Using the six test tubes from step 4, add 5 ml of sodium carbonate solution to each test tube. Observe and record what occurs in each test tube. Wash out the test tubes.
• Place ½ teaspoon of each sample in a clean test tube. Add 10 drops of Lugol's solution to each test tube. Record your results. Wash out the test tubes.
Procedure, part 2: identification of an unknown substance
You now have the test results for each white powder in Data Table 1. These results will help you to determine the identity of an unknown substance by comparison. Several unknown substances were discovered in student lockers today. Different forensic teams have been asked to identify some of the unknowns. In Data Table 2, write down the number of the zip-lock bag whose contents you will analyze. This number indicates the locker from which the baggie was taken. Compare your results with those in Data Table 1 to determine what substance the student had in his or her locker. Be careful; your results will determine whether or not charges should be pressed against the student.
• Write down the locker number on the bag in Data Table 2.
• Perform all the tests you performed in part 1 on this unknown substance. Record your findings in Data Table 2.
• Compare the results in Data Table 2 with the results in Data Table 1.
Postlab Questions (answer the following questions in complete sentences on your own paper):
• Describe one positive test from Data Table 1 for each of the six powders.
• Was the powder you examined in Part 2 one of the illegal drugs or was it table salt? Explain how you arrived at this conclusion.
• Explain why forensic scientists must be very accurate when examining substances in the laboratory.
• Explain why Part 1 was a vital part of this experiment.
DATA TABLE 1 Observations of Tests Performed on Known Substances
Name of Known SubstanceObservation with Hand LensHot Plate ResultsAddition of WaterAddition of Sodium CarbonateAddition of Acetic AcidAddition of Lugol''s solution A: Escape B: Peppy C: Vavoom D: Droop E: Bang F: Table Salt
DATA TABLE 2 Reaction of Powders to Chemical Tests
Hand Lens ObservationHot Plate ResultsAddition of WaterAddition of Sodium CarbonateAddition of Acetic AcidAddition of Lugol's Solution Unknown Sample #__________
Teacher Notes: Forensics and Unknown Powders
This lab requires a 50-minute class period. Prepare 1M sodium carbonate by adding 53 grams of sodium carbonate powder to 500ml of distilled water. When it combines with calcium chloride solution, a precipitate of calcium carbonate will form. Do not tell the students the actual identity of the substances you are using to represent the illegal drugs but do stress to the students that the substances they are working with are NOT REALLY illegal drugs. After the lab you may wish to discuss precipitates, positive Lugol's test for starch, and the reaction of sodium bicarbonate and vinegar to produce carbon dioxide bubbles. Use the following substances for the six white powders: A: Baking soda B: Calcium chloride C: Corn starch D: Plaster of Paris E: Table sugar F: Table salt Prepare small zip-lock bags with about ¼ cup of each of the six substances. Label the bags with the proper letters. Prepare enough bags so each lab group will have six different bags. For Part 2, select a different substance for each lab group and place it in a small plastic bag. Write a number on each bag that represents the locker number in which the substance was found. Keep records of what numbers match which substances.
Accommodations:
• Model the different procedures to be used for the lab
• Allow extra time to answer the questions and fill out data tables
• Group students in the labs to allow for peer tutors
• Allow students to divide up the tests so each can perform a procedure in which they will be successful and can then share their results with the group
Scoring:

Data Table 1
All results thoroughly recorded	30
Every space has writing but it is not thorough or completely accurate	20
Missing observation data (some blanks)	15
Data table is only partially complete (half finished)	10
Less than half of the data is present	5
Data Table 2
Data table is complete and observations are well written	15
Data table missing 1 or 2 observations, observations lack detail	10
Data table missing 3 or 4 observations, observations lack detail	5
Questions
Each questioned answered correctly, thoroughly and in a complete sentence	20
Each questioned answered correctly, lacks supporting details, may not be a complete sentence	15
One question not answered, not complete sentences, incorrect response	10
Two questions not answered, or incorrect	5
TOTAL :	65 points

Forensics and Dirt: A Lab on the Evidence from Soil
Background:
What exactly is dirt or soil? The definition of soil can vary depending on whom you ask. Farmers consider soil to be the top 6 to 12 inches of the earth's crust where plants grow. Geologists-scientists who study the earth''s surface define soil as the organic (carbon-containing) and mineral matter composing the earth. Engineers look at soil as material that can be removed from an excavation site. Forensic geologists consider soil as earth material that has been collected accidentally or on purpose and is related to the matter being investigated. When a forensic geologist is investigating a crime, all natural and artificial objects that are on or near the surface of the earth are considered part of the soil. This includes rock, minerals, vegetation, glass, paint, asphalt, etc. The presence of these objects in that area helps to make that area of soil unique from other areas. Many scientists agree that no two places on Earth have precisely the same soil. Soil from one area will be identifiably different from the soil collected in another location. The properties of soil also vary depending on the depth from which the sample is taken. In most forensics cases, only about one cup of the top layer of soil needs to be collected. The sample should be allowed to air dry to prevent further decomposition of the material in the soil. Once dry, it is transferred to the crime lab to compare with the soil sample that was found on the suspect or on his or her belongings. Once in the crime lab, scientists use color as their main identification technique. Before observing the color, all samples are further dried at 100 degrees Celsius for one hour because wet soil will appear as a different color from dry soil. The presence of certain minerals in the soil can give it a characteristic color. For example, the presence of copper minerals appears green while black minerals point to the presence of manganese and iron. Odor and texture of soils are also examined during the initial observation.
In this lab you will:
Learn how to perform various tests on soil, which will enable you to compare soil samples and possibly match them to a suspect of a crime.
Here's the Story:
Monica's house was robbed last night while she and her family were out for dinner. The police discover a torn window screen and a broken window latch on the back bedroom window. They believe this is how the burglar entered the home. Heavy rain that night washed away any trace of footprints. The crime scene investigators feel that the burglar might have a lot of dirt and debris caked on his shoes. Therefore, they take a soil sample from outside the window and send it back to the lab. Early this morning, police bring in four suspects who cannot account for their whereabouts last night. The police scrape the bottom of each of their shoes and send these scrapings to the crime lab for comparison with the soil outside the window of Monica's house. Your job is to determine if the soil from any of the suspects' shoes matches the soil at the crime scene. Each soil sample has been dried for 1 hour at 100 degrees Celsius.
Part 1: Materials
5 petri dishes 5 soil samples (in labeled plastic bags) Stereomicroscope
Procedure:
• Label five petri dishes with the following letters: CS: Crime scene (this is the known sample from Monica's house) S1: Soil from Suspect 1 S2: Soil from Suspect 2 S3: Soil from Suspect 3 S4: Soil from Suspect 4
• Sprinkle enough of each soil sample in the appropriate petri dishes to cover the bottom of the dishes.
• In Data Table 1, record the following about each soil sample:
• Colors
• Odors
• Textures (grainy, smooth, hard, etc.)
• Presence of plant or animal debris
• Presence of inorganic (nonliving) material
• Repeat step 3 using the stereomicroscope. Record your findings on Data Table 2. This time, give a more detailed description of each sample.
Part II: Testing pH, Nitrogen, Phosphorus and Potassium Levels
Materials:
5 labeled soil samples LaMotte soil testing kit(s)
Procedure:
• Follow the directions as illustrated in the test kit.
• Create your own data table to record the testing information.
Part III: Soil Texture Unit
Materials:
5 labeled soil samples LaMotte's soil texture test kit
Procedure:
• Follow the directions as written with the test kit.
• Create a data table to record your test information.
Postlab Questions (answer the following questions with complete sentences and on your own paper):
• Compare samples from Suspects 1 through 4 with the sample from the crime scene and determine if you have a match. Which suspect committed the crime?
• What is soil?
• Why were the soil samples dried before observations were made?
• Did any of your soil samples have the same data results when testing for pH, nitrogen, phosphorus or potassium? If so, which ones?
• Did any of the soils end up having the same percentage of sand, silt and clay? If so, which ones?
• Why do you feel you had to perform so many different tests on these soils to determine a match?
Data Table 1 Initial Descriptions
SampleColorOdorTexturePlant or Animal DebrisInorganic Debris Present CS S1 S2 S3 S4
Data Table 2 Observation with Microscope
SampleColorTexturePlant or Animal DebrisInorganic Debris Present CS S1 S2 S3 S4
Teacher Notes: Forensics and Dirt
• The students will need one day for Part 1 and an additional day to complete Parts 2 & 3.
• You will need to collect soil from 4 different locations. You may want to "doctor" the samples by adding chemicals, glass shards, animal & plant debris, etc.
• Dry each sample of soil in the oven for an hour at 100 degrees Celsius.
• Decide which of the four samples you want to call "CS" (the sample from the crime scene) and place part of that sample in a plastic bag. Label that bag as "CS." Label the other four bags as 1, 2, 3, and 4. Fill them with the four soil samples.
• You will need a LaMotte soil testing kit for each lab group as well as a LaMotte soil texture kit. The directions are included with the kits and are exceptionally easy to follow.
Accommodations:
• You may have the group turn in one of each data table instead of each individual.
• Allow extra time, if needed, to complete the tests and to create and fill out the data tables.
• Group the students to provide peer tutors within the lab.
• Divide up the procedures according to skill level.
Scoring:

Data tables 1 and 2	20 (10 points each)
Chemicals in soil data table	20
Soil texture data table	20
Questions	30
Total score:	90 points

A CRIME HAS BEEN COMMITTED: CRIME RESEARCH TEAM NEEDED
Police Report:
Friday night a murder was committed. The victim has been identified as a 17-year-old male. At 11:00 P.M. a gentleman who was out walking his dog discovered him. The victim has been severely beaten and hit by a car. Before he was removed from the crime scene, a forensic team was called in to investigate.
The following evidence was collected from the crime scene:
• Broken glass on the ground near the victim
• Samples of lipstick found on the victim's lips and cheek
• Dirt from the ground around the crime scene
• Powder samples from a small zip-lock bag found in the victim's inside jacket pocket
• Blue material fibers from the victim's hand that did not match anything the victim was wearing
Interviews with the victim's family and friends revealed the following:
• The victim did not have a steady girlfriend.
• The victim was interested in a girl from his science class but she has an extremely jealous boyfriend.
• The victim's parents and friends said he did not use drugs.
• The victim's best friend said that the victim was excited about meeting someone Friday night but that he wouldn't give any details.
The Police have six suspects. Searches have been conducted and the following is what was collected:
Suspect #1: female
• lipstick sample
• blue jacket
Suspect #2: female
• lipstick sample
• dirt from her car floor
• white powder found in a zip-lock bag in her bedroom
Suspect #3: female
• lipstick sample
• blue jacket
Suspect #4: male
• sample of headlight glass
• dirt from car floor
• powder residue on car seat
Suspect #5: male
• sample of glass from headlight
• dirt from bottom of shoes (car had been detailed on Saturday before the police arrived)
• blue shirt
Suspect #6: male
• sample of headlight glass
• dirt from car floor
• powder found inside pocket of blue jacket
• blue jacket
Procedure:
• Obtain samples of each piece of evidence found at the crime scene.
• Label each piece of evidence.
• Obtain samples of all the items found with each suspect.
• LABEL.
• Follow the procedures from your previous labs to analyze the evidence.
• Create a separate data table for each piece of evidence found at the crime scene and how it compares with the evidence from the suspects. (5 separate data tables!!!!)
• Create a data table or graphic organizer that supports who you feel committed the crime.
• Write a story about the events leading up to the crime. Include in your story: motive, all the evidence, how the crime occurred and what the suspect(s) did after the crime. Use correct spelling and grammar.
Teacher Notes: A Crime Has Been Committed
The most difficult part of this activity is setting it up. You will have to decide well in advance of the activity which lipstick, soil sample, fiber, glass and powder you will use for that found at the crime seen and on the suspects. You may set up the crime to have only one person guilty, 2 guilty or none of the given suspects guilty. The main objective is to have the students investigate the evidence using proper procedures, organizing that information and drawing a reasonable conclusion that they can support with the given results. It will take at least five class periods for the students to conduct their investigation and I would allow a minimum of one class period for them to organize all of their data and create their story. The materials that you will need are the same as those used in the labs leading up to this crime. I give students very little direction for this activity. They should already know how to analyze the evidence and what materials they will need from doing the training labs up to this point. Them following proper procedure is part of their grade.
Accommodations:
• This lab requires a lot of organization. Increase the amount of personal assistance in the initial organization of the investigation.
• Guide students to the appropriate pages and data tables on the previous labs to help organize their procedures and information.
• Give the students the scoring guide before they start the assignment so they can keep track of what is expected of them.
• Allow the students to assign different tasks to one another so everyone in the group has a job he/she can be successful in completing.
• Require only one of each data table per group instead of each individual.
• Require only one story per group instead of from each individual.
• Some students are very creative with stories but have a difficult time converting the oral to the written. Have a student who has good written skills write the story that the students with good oral skills create.
INDIVIDUAL SCORING GUIDE FOR "A CRIME HAS BEEN COMMITTED"
1 2 3 4 5

5=ALWAYS, 4=MOST OF THE TIME, 3=OBSERVED HALF THE TIME, 2=OBSERVED, BUT NOT OFTEN, 1= RARELY OBSERVED
Has read and seems to understand all experimental procedures prior to their beginning.
Is attentive to the instructor and others working within the laboratory area.
Has taken all safety precautions and follows safety regulations adequately.
Observes adequately and records thoroughly what has been observed.
Labels everything used in the lab.
Classifies items, thoughts, or observations in an organized and methodical manner.
Uses self-direction and exhibits common sense in the setting up of experimental apparatus so as to measure correctly.
Draws insight from questions, past procedures or earlier explanations.
Predicts proposed results prior to collecting and analyzing the data gathered.
Carefully and effectively gathers measurements and observations in an adequate quantitative manner.
Carefully and effectively gathers measurements and observations in an adequately qualitative manner.
Communicates appropriately with co-workers.
Organizes collected data in visual patterns for a more definitive illustration and interpretation of it.
Recognizes incompatibilities in gathered observations or data samples.
Adequately interprets results from organized data samples and properly notes relationships.
Hypothesizes as to why a procedure did or did not yield successful results.
Experiments with equipment and equipment set-ups in order to yield more consistently valid results.
Experiments safely with procedures and techniques so as to yield more consistently valid results.
Exhibits proper overall laboratory technique.
Does verify results properly.
Is able to communicate the results of an experiment effectively to others.
TOTAL POSSIBLE:	105 POINTS

GROUP SCORING GUIDE FOR "A CRIME HAS BEEN COMMITTED" 10 5 1 Score Evidence Data Tables (times 5) Graphic Organizer (times 3) Story (times 3) Total Score

All 5 data tables are present. All tables are properly labeled, including a title. All data is properly and clearly entered.	Missing a data table. Tables not clearly labeled or titled. Missing data.	Missing more than one table. Unclear labeling. Missing a lot of data.
Titled. Clearly shows how the evidence leads to the conclusion.	Untitled. Good attempt but not completely clear how evidence leads to conclusion.	Confusing. Cannot figure out how things relate.
Less than 3 spelling and grammar errors. Includes motive, how crime occurred, all of the evidence, what happened after the crime. Creative.	More than 3 but less than 10 spelling and grammar errors. Includes all of the requested components. Lacks creativity.	More that 10 spelling or grammar errors. Missing one or more of the requested components.

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For additional information contact :
Stacey Endebrock
Hillsboro High
Hillsboro R-III
(636) 789-0010
EMAIL: paintedridge1@aol.com