Life Science: Forensics
Teacher’s Guide
Grade Level: 6–8
Curriculum Focus: Life Science
Lesson Duration: 1 class period
Program Description
The work of forensic scientists is featured in several popular television programs. And it’s no wonder.
The science of reconstructing the past to solve a crime or mystery is fascinating. Fingerprinting and
DNA analysis are two methods of identifying culprits based on qualities unique to individuals. Other
methods of examining evidence can reveal the authenticity of a painting, help uncover the cause of
death of a long-dead king, or prove whether a fire was set intentionally. Forensics shows that no matter
how careful a criminal might be or how old the evidence, there are still clues that can lead to the truth.
Discussion Questions
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What is forensic science?
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What are the three fingerprint patterns analysts look for in making a match?
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What is DNA, and how does DNA analysis help identify or eliminate criminal suspects?
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What are some of the methods used to look for forgery in a painting?
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What kinds of information can be learned from a forensic study of a mummy?
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What kinds of evidence can remain even after a destructive fire?
Lesson Plan
Student Objectives
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Define forensic science and understand how it is used to solve crimes and answer
questions about the past.
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Extract DNA from cheek cells.
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Understand how DNA analysis is an excellent forensic tool.
Materials
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Salt
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Distilled water
Life Science: Forensics
Teacher’s Guide
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Disposable plastic cups
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Liquid soap
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Test tubes and stoppers
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Ethanol (grain or ethyl alcohol) that’s been in the freezer or on ice
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Twist ties
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Computer with Internet access
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Print resources about forensic science
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Procedures
1. DNA is one of the most recent and effective forensic tools. DNA analysis can place a person at a
crime scene or exonerate someone accused of a crime because, like fingerprints, everyone’s
DNA is unique. Students have probably seen TV detectives swab a suspect’s cheek to get a
DNA sample. In this activity, students will be able to extract DNA from their own cheeks.
2. Go to this Nexus Research Group page to find simple instructions for extracting cheek DNA:
http://www.nexusresearchgroup.com/fun_science/dna.htm. The PBS NOVA page Cracking the Code
of Life also has directions for conducting this experiment. It’s at
http://www.pbs.org/wgbh/nova/teachers/activities/2809_genome.html.
3. Once everyone has finished the procedure and examined his or her own DNA. Wrap up with
these discussion questions:
• Where does the DNA come from? (the nucleus of the cells)
• How is the DNA isolated in the experiment? (The liquid soap breaks through the cheek
cell membranes, releasing the DNA and other cell components. The ethanol separates
the DNA from everything else.)
• Is this procedure similar to what forensic scientists do when extracting DNA? (Yes. Once
they’ve extracted the DNA, they then process it to reveal the patterns found in specific
segments, as shown in the video.)
4. To explore other forensic techniques, look to these activities:
• The Forensic Science page of Discovery School’s Lesson Plan Library contains seven
activities for middle school students, covering crime solving skills and forensic
anthropology.
http://school.discovery.com/lessonplans/forensics.html
• “Killer’s Trial” is the site that accompanies the PBS NOVA program of the same name.
There you can find numerous activities relating to solving the famous 1954 case of the
murder of Marylin Sheppard.
http://www.pbs.org/wgbh/nova/sheppard/
• Whodunit? is an Explore@Bristol site. The Teacher Resources page contains lesson plans
and PDF files to conduct 17 forensic activities.
Published by Discovery Education. © 2005. All rights reserved.
Life Science: Forensics
Teacher’s Guide
http://www.at-bristol.org.uk/explore/Whodunit/teachers.htm
Assessment
Use the following three-point rubric to evaluate students’ work during this lesson.
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3 points: Students were highly engaged in class discussions, successfully extracted DNA
from their cheek cells, and thoughtfully answered the follow-up questions.
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2 points: Students participated in class discussions, extracted DNA from their cheek cells,
and answered some of the follow-up questions.
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1 point: Students participated minimally in class discussions; were unable to extract DNA
from their cheek cells or did not perform the procedure carefully, and did not thoughtfully
answer follow-up questions.
Vocabulary
arc, loop, and whorl
Definition: The three patterns experts look for in fingerprints
Context: Placement and appearance of arcs, loops, and whorls in fingerprints are what make
them unique to each person.
arson
Definition: The crime of deliberately setting a fire
Context: Forensic techniques such as examining broken glass can help determine whether a fire
was an accident or arson.
chromatography
Definition: The technique of separating solid mixtures or gases into their various components
Context: Chromatography can break down a liquid found at a fire to determine whether it was
an accelerant.
DNA
Definition: An acid found in a cell nucleus that carries the genetic information a cell needs to
replicate
Context: DNA is short for deoxyribonucleic acid and is unique in every individual.
embalming
Definition: The process of preserving a dead body
Context: Because mummies were carefully embalmed, forensic scientists can learn a great deal
by studying their remains.
forensic science
Definition: The analysis of evidence to reconstruct past events and solve criminal cases
Published by Discovery Education. © 2005. All rights reserved.
3
Life Science: Forensics
Teacher’s Guide
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Context: Fingerprinting, DNA analysis, and chromatography are just a few of the tools used in
forensic science.
forgery
Definition: A fake or counterfeit
Context: A forgery can be a faked signature on a bank account or a painting made to look like
the work of a famous artist.
Academic Standards
National Academy of Sciences
The National Science Education Standards provide guidelines for teaching science as well as a
coherent vision of what it means to be scientifically literate for students in grades K–12. To view the
standards, visit this Web site:
http://books.nap.edu/html/nses/html/overview.html#content
This lesson plan addresses the following national standards:
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Life Science: Structure and function in living systems
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Science and Technology: Understandings about science and technology
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Science in Personal and Social Perspectives: Science and technology is society
Mid-continent Research for Education and Learning (McREL)
McREL's Content Knowledge: A Compendium of Standards and Benchmarks for K–12 Education
addresses 14 content areas. To view the standards and benchmarks, visit
http://www.mcrel.org/compendium/browse.asp
This lesson plan addresses the following national standards:
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Science: Life Sciences—Understands the structure and function of cells and organisms;
Nature of Science—Understands the nature of scientific inquiry; Understands the scientific
enterprise
Support Materials
Develop custom worksheets, educational puzzles, online quizzes, and more with the free teaching tools
offered on the Discoveryschool.com Web site. Create and print support materials, or save them to a
Custom Classroom account for future use. To learn more, visit
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http://school.discovery.com/teachingtools/teachingtools.html
Published by Discovery Education. © 2005. All rights reserved.