Affordable Forensics Fun
Jocelyn Koller
University of Maryland Extension 4-H STEM Associate Agent
The University of Maryland Extension programs are open to all and will not discriminate against anyone
because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, or national
origin, marital status, genetic information, or political affiliation, or gender identity and expression.
Three affordable forensics lessons:
1. Fingerprints
2. Ink Chromatography
3. Toolmarks
For each lesson, we will:
Perform
Hands-on
Investigation
Apply to
Broader
Scientific
Topics
Discuss Lab
Safety
Fingerprints
Why do we have fingerprints?
There are three types of fingerprints:
1. Plastic- impression
2. Latent- invisible to the naked eye
3. Patent- visible prints
Plastic Fingerprints
Definition: Fingerprints that leave ridge impressions in a substance, i.e. mud, clay
Plastic Fingerprint Exercise
Materials needed:
Play dough
Directions:
Ask youth to press into the play dough and view the ridge impressions. Use a
magnifying glass, if needed.
Latent Fingerprints
Definition: Fingerprints that are invisible to the naked eye.
Latent Fingerprint Exercise
Materials needed:
Magnifying glass, or smooth glass/plastic like surface
Directions:
Ask youth to rub fingers through their hair to pick up oils. Then place a fingerprint
on the magnifying glass and view. Use another magnifying glass, if needed.
Patent Fingerprints
Definition: Fingerprints that are visible to the naked eye.
Patent Fingerprint Exercise
Materials needed:
Magnifying glass, ink pad, FBI Applicant fingerprint card, Ink remover wipes, Loop, Whorl,
Arch cards, Pen/Pencil
Directions:
Ask youth to complete the FBI Applicant fingerprint card. Then, ask youth to fold the card
at the line under right and left fingerprints. Roll fingerprints in ink pad to obtain a full print.
The roll the finger in the corresponding box.
Patent Fingerprints
Patent Fingerprint Exercise Continued
Directions:
Ask youth to use a magnifying glass and the loop, whorl, and arch cards to identify
his/her fingerprint patterns. Write L, W, or A in the boxes to identify the prints.
Patent Fingerprints
Patent Fingerprint Exercise Continued
Image taken from: http://eisforexplore.blogspot.com/2012/12/are-you-loop-arch-or-whorl.html
Fingerprints
Broader Scientific Applications
Physics- Friction
BiologyIntegumentary System
Genetics- Uniqueness
Ink Chromatography
Adapted from: http://www.msichicago.org/fileadmin/Education/learninglabs/lab_downloads/EL_ink_chromatography.pdf
Introduction: Ink chromatography allows us to separate and analyze the colored pigments
that make up markers. Even though a marker writes in only one color, there may be hidden
pigments in the marker that you cannot see. Ink chromatography will allow you to see all
pigments inside of a marker by creating a chromatogram.
Ink Chromatography
Materials needed:
Coffee filter, Black Marker (variety of brands), Scissors, Plastic Cup, Wooden coffee stirrer,
Alcohol, Pencil, Note written in black marker, Ruler, Calculator
Lab Safety:
1.
Wear safety goggles
2.
Alcohol is flammable. Store accordingly.
Ink Chromatography
Procedure:
1. Cut a 1’’ strip of paper from the coffee filter.
2. Cut the end of the strip so it makes a ‘V’.
3. Choose a marker to test. Record the marker brand name:
______________________________________
4. Using the marker, draw a line from one side of the strip of paper to other.
5. Pour about 1’’ of alcohol into a plastic cup.
6. Place the pointed end of the strip of paper into the alcohol, but make sure the
marker line stays above the alcohol.
7. Put a wooden coffee stirrer through the top of the strip to hold the
chromatogram in place.
8. The alcohol will begin moving up the strip and will carry with it the ink
pigments.
9. Wait about 10 minutes for your chromatogram to develop.
Toolmarks
Adapted from: http://sciencespot.net/Media/FrnsScience/toolmarkchallinfo.pdf
Introduction: When two objects come in contact with each other, the harder object
will leave an impression in the softer such as in the case of toolmarks. Toolmark
analysis is used to compare tools to toolmarks found at the crime scene.
Toolmark Analysis
Materials needed:
Variety of tools, clay, card stock, ruler, magnifying glass, pen/pencil
Lab Safety:
1. Wear safety goggles.
2. Choose youth-appropriate tools
3. Remind youth how to exchange tools
Toolmarks
Directions: Complete Investigation 1 by filling out the chart, then match the toolmarks in Investigation 2.
Tool
Number
Tool Name
Drawing of
Tool
Width of Length of
Tip
(mm)
1
2
3
Tip (mm)
Observations
Marking in Clay
Toolmarks
Analysis Questions:
1. How might the marks of a new tool differ from a used tool?
2. How could one screwdriver produce two very distinct markings?
3. Do you think the markings of two identical tools (new and from the
same manufacturer) would leave identical markings?
Toolmarks
Broader Scientific Applications
PhysicsPressure/Friction
MeasuringMillimeters/Using a ruler
Biology- Comparison
Microscopes
Ink Chromatography- Continued
Procedure Continued:
10. When the alcohol has finished moving up the strip of paper, remove the paper from the cup and place it on
a paper towel.
11. Each brand of marker produces a different combination of color pigments.
12. View the chromatogram, record how many different colors are present :___________
13. Record the colors in the chart below.
14. Now, you will calculate the retention factor (Rf) of each color pigment.
15. Measure in millimeters from the original marker line to the farthest line where the alcohol traveled. Record
this measurement in third column of your chart.
16. Calculate the same measurement for each color pigment on your chromatogram in the chart below.
17. To determine the Rf value for each pigment use this formula:
Rf value= Distance traveled by color pigment/Distance traveled by alcohol
10. Record the Rf values for each color pigment.
Ink Chromatography
Ink Chromatography Continued
Analysis:
Color
Color- Millimeters traveled
Alcohol- Millimeters traveled
Rf value
1. A solvent dissolves a substance, and a solute is the dissolved substance. Based on
these definitions, what are the solvent and solute in this lab?
2. Which marker matched the note? How do you know? Is this enough to link a
suspect to the note?
Ink Chromatography
Broader Scientific Applications
Chemistry- Solutes and
Solvents
MeasuringMillimeters/Using a ruler
Conclusion
There are affordable, low-tech forensics hands-on labs.
Remember to focus on the science and evidence, not the crime
Choose age appropriate scenarios, such as stolen lunch money, or a
book bag taken from a locker.
Remember lab safety!
Use forensics to make broader scientific applications and to increase
knowledge of basic science lab skills.
Questions?
Please contact me at:
Jocelyn Koller
UME 4-H STEM Associate Agent
jckoller@umd.edu