1. 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.

2. Three affordable forensics lessons:
Fingerprints
Ink Chromatography
Toolmarks
For each lesson, we will:
Perform Hands-on Investigation
Apply to Broader Scientific Topics
Discuss Lab Safety

3. Fingerprints Why do we have fingerprints?
There are three types of fingerprints:
Plastic- impression
Latent- invisible to the naked eye
Patent- visible prints

4. 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.

5. 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.

6. 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.

7. 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.

8. Patent Fingerprint Exercise Continued
Patent Fingerprints
Patent Fingerprint Exercise Continued
Image taken from:

9. Broader Scientific Applications
Fingerprints
Physics- Friction
Biology- Integumentary System
Genetics- Uniqueness

10. Ink Chromatography Adapted from: http://www. msichicago
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:
Wear safety goggles
Alcohol is flammable. Store accordingly.

11. Ink Chromatography Procedure:
Cut a 1’’ strip of paper from the coffee filter.
Cut the end of the strip so it makes a ‘V’.
Choose a marker to test. Record the marker brand name: ______________________________________
Using the marker, draw a line from one side of the strip of paper to other.
Pour about 1’’ of alcohol into a plastic cup.
Place the pointed end of the strip of paper into the alcohol, but make sure the marker line stays above the alcohol.
Put a wooden coffee stirrer through the top of the strip to hold the chromatogram in place.
The alcohol will begin moving up the strip and will carry with it the ink pigments.
Wait about 10 minutes for your chromatogram to develop.

12. Toolmarks Adapted from: http://sciencespot
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:
Wear safety goggles.
Choose youth-appropriate tools
Remind youth how to exchange tools

13. 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 Tip (mm)
Length of Tip (mm)
Observations
Marking in Clay 1 2 3

14. Toolmarks Analysis Questions:
How might the marks of a new tool differ from a used tool?
How could one screwdriver produce two very distinct markings?
Do you think the markings of two identical tools (new and from the same manufacturer) would leave identical markings?

15. Broader Scientific Applications
Toolmarks
Physics- Pressure/Friction
Measuring- Millimeters/Using a ruler
Biology- Comparison Microscopes

16. Ink Chromatography- Continued
Procedure Continued:
When the alcohol has finished moving up the strip of paper, remove the paper from the cup and place it on a paper towel.
Each brand of marker produces a different combination of color pigments.
View the chromatogram, record how many different colors are present :___________
Record the colors in the chart below.
Now, you will calculate the retention factor (Rf) of each color pigment.
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.
Calculate the same measurement for each color pigment on your chromatogram in the chart below.
To determine the Rf value for each pigment use this formula:
Rf value= Distance traveled by color pigment/Distance traveled by alcohol
Record the Rf values for each color pigment.

17. Ink Chromatography Ink Chromatography Continued Analysis:
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?
Which marker matched the note? How do you know? Is this enough to link a suspect to the note?
Color
Color- Millimeters traveled
Alcohol- Millimeters traveled
Rf value

18. Broader Scientific Applications
Ink Chromatography
Chemistry- Solutes and Solvents
Measuring- Millimeters/Using a ruler

19. 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.

20. Please contact me at: Questions? Jocelyn Koller
UME 4-H STEM Associate Agent