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Hunt for the Serial Arsonist

Classroom Activity

Objective
To prepare, study, and graph fingerprint patterns.

• copy of "At Your Fingertips" student handout (one for each student) (PDF or HTML)
• a new notepad or unopened package of white paper
• black tempera paint powder
• transparent tape
• a sheet of newspaper
• a hand-held lens

1. One fingerprint led to the identification of the arsonist in this program. Fingerprint analysts look for distinguishing features as a means of classifying the prints they investigate. Some of the features mentioned in the program are bifurcations, ending ridges, and dots. To give your students an opportunity to observe and collect fingerprints, conduct this activity.

2. Distribute copies of the "At Your Fingertips" student handout to each student.

3. After students have recorded their fingerprints, have them look for some common features in their prints. Certain fingerprint features are more common than others.

4. Create a graph showing the distribution of different patterns within your class. Start with a sample of ten students' fingerprints, and have the students predict the distribution of each pattern in the general population. Add data from another 10 students to the graph. Review the students' earlier prediction. How have the percentages changed? What trends are becoming evident? Add the data from any remaining students, then share the statistics from the answer page with the rest of the class. How do the fingerprints in your class compare to the general population?

The loop pattern is dominant in 65 percent of the population; the whorl pattern is dominant in approximately 30 percent; and the arch pattern is dominant in approximately 5 percent. Although students will discover that their own class resembles this statistical spread to some extent, they should also recognize the additional features that make their own fingerprints unique. Students should observe sections of their fingerprints to identify particularly noticeable features, which could be used to identify them. In addition, they should look for other fingerprint features that they weren't born with that someone could use to identify them (such as scars or warts).