- The focus of the story is on the forensics used to solve crimes. How did Erin collect DNA samples from here suspects? Was this legal?
- Think about one of the minor characters in the story. Why did the author include him/her?
- What do you think the author was trying to accomplish with this novel? Has it sparked any interest in forensic science for you?
CSI Science: Get the Prints!
Learning Outcomes Statement:
CSI Science: Get the Prints will engage students in hands on investigation, allowing them to collect and analyze fingerprints. This will develop the core academic skill of problem solving by having the students support possible solutions with facts and details.
- Index card or piece of white paper
- Transparent tape or clear packing tape
- Talcum powder or cornstarch
- Small paint or makeup brush with very soft bristles
- Spoon or drinking glass
- Magnifying glass
- Cocoa powder
Library Resources/Materials to Share:
363.25 MURRAY Forensic Identification: Putting a Name and Face on Death by Elizabeth A. Murray
FIC SCARBOROUGH, S. To Catch A Killer by Sheryl Scarborough
Y 576.078 GARDNER Genetics and evolution science fair projects, revised and expanded using the scientific method by Robert Gardner
Y 571.60078 RAINIS Cell and microbe science fair projects using microscopes, mold, and more by Kenneth G. Rainis
LAFS.910.RST.1.1: Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.
LAFS.910.RST.1.2: Determine the central ideas or conclusions of a text; trace the text’s explanation or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the text.
SC.912.L.16.In.3: Recognize that a substance called DNA carries genetic information in all organisms, and changes (mutations) in DNA can be helpful or harmful to an organism
SC.912.L.16.Su.2: Recognize that all organisms have a substance called DNA with unique information.
Notes for Introduction:
We’ve been reading about forensic investigations. What are some clues that law enforcement looks for at a crime scene? (Blood spatter patterns, footprints, tire treads, fingerprints etc.)
The patterns of ridges on our fingers are unique. No two individuals, even identical twins, have fingerprints that are exactly alike. We leave impressions, or prints, of these patterns on everything we touch. Sometimes the prints are visible, such as when our fingers are dirty or oily. Other times they’re “latent” and are made only by the sweat that is always present on our finger ridges. Not even injuries such as burns or scrapes can change the fingerprint structure.
- The easiest method to take a fingerprint is to rub pencil lead all over a small area of paper or index card to make an “ink” pad. Press your fingers onto the penciled area, then lift the prints from your fingers with transparent tape and place the tape on a white index card for reading.
- Before the activity, place your fingerprints on some common classroom objects such as computer screens, desktops, and white boards.
- Have the students look at their fingerprints with a magnifying glass and try to identify what type they have. The Federal Bureau of Investigation categorizes prints by three main patterns: arches, loops, and whorls. Have your students use the Internet to find pictures to help identify the unique characteristics of their fingerprints.
- To dust for fingerprints, sprinkle talcum powder or cornstarch on dark surfaces and cocoa powder on light surfaces where you left visible prints. Have the students use the small paint or makeup brush to gently swipe off the excess powder.
- Next place a large piece of transparent tape, or clear packing tape, over the print, carefully peeling off the fingerprint and placing it on an index card or piece of white paper. Challenge students to identify the arches, loops, and whorls within the lifted “latent” fingerprints to see who it belongs to.
Extension: Certain chemical fumes react with the perspiration or organic residue left in a fingerprint. Have your students experiment for themselves: all they need is a square of aluminum foil folded in fourths, a glass jar, “Superglue,” and a smooth object like an ink pen. They should wipe down the object and then hold it for a minute so that their fingers leave prints. Set the object inside the jar. Next, put several drops of superglue on the middle of the pie plate and turn the jar upside down over it. The strong chemical fumes from the cyanoacrylate in the glue will react with the residue from fingers enabling them to see white fingerprint images on the object after about half hour.
Questions for Feedback and Reflection:
- Is it possible that two people could have identical fingerprints?
- In what ways besides solving crimes can fingerprint identification be used?
- Nowadays, police seem to prefer DNA evidence to fingerprint evidence. Why do you think this might be the case?
- Not everyone’s fingerprints are in the FBI’s computer database. Generally, only people who work for the government, immigrants to the United States, and those people who have been arrested have their fingerprints saved. Do you think everyone in the United States should have their fingerprints taken? Why or why not?