T. Trimpe 2006 http://sciencespot.net

Fingerprint Principles

According to criminal investigators, fingerprints follow

3 fundamental principles:

• A fingerprint is an individual characteristic; no two

people have been found with the exact same

fingerprint pattern.

• A fingerprint pattern will remain unchanged for the

life of an individual; however, the print itself may

change due to permanent scars and skin diseases.

• Fingerprints have general characteristic ridge patterns

that allow them to be systematically identified.

Fingerprint Classes

There are 3 specific classes for all fingerprints based

upon their visual pattern: arches, loops, and whorls.

Each group is divided into smaller groups

as seen in the lists below.

Arch

Plain arch

Tented arch

Loop

Radial Loop

Ulnar loop

Whorl

Plain whorl

Central pocket whorl

Double loop whorl

Accidentical

Interesting Info

Did you know?

Dactyloscopy is the study of fingerprint identification.

Police investigators are experts in collecting

“dactylograms”, otherwise known as fingerprints.

Fingerprint Factoid:

60% of people have loops, 35% have whorls,

and 5% have arches

ArchesArches are the simplest type of fingerprints that are formed by

ridges that enter on one side of the print and exit on the other. No

deltas are present.

Plain Arch

Ridges enter on one side and

exit on the other side.

Tented Arches

Similar to the plain arch,

but has a spike in the center.

Spike or “tent”

Loops

Loops must have one delta and one or more

ridges that enter and leave on the same side.

These patterns are named for their positions

related to the radius and ulna bones, i.e. the

bone the loop opening is facing towards.

Delta

L – Radial Loop

R - Ulnar LoopL – Ulnar Loop

R - Radial Loop

Radius

Ulna

Left

Hand

X-Ray Imagine: http://www.tooloop.com/wp-content/uploads/2013/12/Radius-Ulna-X-Ray.jpg

WhorlsWhorls have at least one ridge that makes (or tends to make) a

complete circuit. They also have at least two deltas. If a print has

more than two deltas, it is most likely an accidental.

Draw a line between the two deltas in the plain and central pocket

whorls. If some of the curved ridges touch the line, it is a plain

whorl. If none of the center core touches the line, it is a central

pocket whorl.

Plain

Whorl

Central

Pocket

Whorl

Whorls – Part 2

Accidental Whorl

Accidental whorls contain two

or more patterns (not

including the plain arch), or

does not clearly fall under any

of the other categories.

Double Loop Whorl

Double loop whorls are

made up of any two loops

combined into one print.

Delta

Delta

Identify each fingerprint pattern.

Right Hand

Left Hand

Left Hand

Right Hand

Right Hand

Lab Write Up• Title: Fingerprint Lab

• Problem: Which is the most

common type of fingerprint

in our class?

`

3 Types of FingerprintsWhorls30-35 % of

people

Arches5 % of people

Loops60-65% of

people

HypothesisHypothesis: If… then…because…

If each person finds their fingerprint type, then the _________ (loop whorl, arch) fingerprint will be the most common because__________

VariablesIndependent Variable (the one thing you

change) – the type of fingerprint

Dependent Variable (the one thing you measure) – the number of fingerprints/percentage of fingerprints

Materials• 1 piece of scratch paper

• 1 pencil

• 1 magnifying glass

• 1 roll of clear tape

Procedure1. Rub the pencil on the scratch paper until there is a

smudge of graphite the size of your fingertip.

2. Select which hand you will take fingerprints from.

3. Beginning with your thumb. Rub it on the smudge until your thumb is covered in graphite.

4. Place a small piece of tape over your thumbprint and press down gently.

5. Carefully remove the tape and stick it in the appropriate square on your data table.

6. Repeat the process for the other 4 fingers of your hand.

7. Look at your fingerprints and identify which type of fingerprint you have.

8. Record the group tallies for each type of fingerprint and then find the total and percentage of each.

Data

Loop

TABLE DATA

`

Identify your type of

fingerprint

Loop

Graph• Create a Bar Graph of your group data in

Google Spreadsheet. (You will copy this

graph into your Lab Doc)

• Title the Graph: Fingerprints

• Title the X- Axis: Types of Fingerprints

• Title the Y-Axis: Percentage of Students

• Remember Percentage is the Number of

the Type divided by the Total Number of

Fingerprints. Ex: 4 Loops from the group/10

Total Fingerprints from the Group = .4

• Then multiply .4 x 100= 40%

After you complete your graph and

lab report…

• Reflect on the answer to your bellwork

question. Add to or revise your

answer based on what we learned in

this lab.

• Then answer the following question:

How will practicing classification

help you understand human body

systems?

• SHARE your Fingerprint Lab

document with me.

When you are finshed