Fingerprint Classification Project
Fingerprint classification is a great science project for kids. Follow these instructions for a great lesson on fingerprinting and the scientific method. This project is great for gifted or older elementary students or for middle school students.
The Question - Can We Devise a System to Classify Fingerprints?
Scientific study requires the collection of large amounts of data, which must be organized in order to be useful. But even kids can come up with useful systems of classification.
- The ridge patterns on our finger pads are unique. No two are exactly alike.
- We leave impressions of these ridges on everything we touch with any pressure.
- Fingerprints can be visible or latent, depending on the substances on our fingers.
- Injuries do not change the ridge structure. New skin always grows in the same pattern.
- Dactyloscopy is the practice of using fingerprints for identification.
Fingerprints are classified by patterns, sizes, and by the position of the patterns on the finger. By using the skills of observation, comparing and contrasting, and classification, students can devise their own system for organizing fingerprint samples.
- 3x5 index cards
- pencil sharpener
- transparent tape (3/4-inch if you can get it)
- good lighting
- magnifying glass
How to Take Fingerprints
- Old school: rubber-stamp ink pads. Watch out for damage to clothing and surroundings.
- Practical: rub pencil all over a small area of paper or index card to make an "ink" pad, press fingers onto the penciled area, lift prints from fingers with transparent tape, and stick tape to white index cards.
In order to use fingerprints to solve crimes, you have to have a way to name and sort them. Then you have to find matching prints to the one you find at a crime scene. The FBI has over 200 million prints on file. Do you think they are able to look at every single one to find a match?
- Separate kids into groups of 4-6.
- They are going to take prints of their thumbs and index fingers to compare.
- You want to make prints not of their tips of fingers but of the pads near the joint crease. That's where the most interesting and distinct patterns are.
- Make sure to label fingerprints with "L" or "R" for left or right hand and "T" or "I" for thumb or index finger.
- Take prints until you get something clear enough to see the pattern.
- After all prints are made and labeled, have partners in each group compare their prints for similarities and differences.
Questions to Explore:
- Are the two prints from the same hand more alike than prints from different people? How?
- What kinds of patterns do they see? (Let them identify patterns they notice before giving them a handout with examples of "official" names for patterns (loops, whorls, and arches).
- What are the positions of those patterns on the finger?
- In which direction do the loops curve-toward the thumb or toward the pinkie finger?
- Compare the size of those patterns.
- Count how many ridges make up a loop.
- Ask which is the most common pattern.
- Present results in graphs, fractions, or percentages.
Go over the original question with kids again. How can fingerprints be classified? Talk about how classification could make it easier to match one print against a database of many. If you have time, you could even create a mock crime scene with a single print from one of your group and time participants while they find a match by examining every single print.