Take the Case: Chain of Evidence

What You Need


  • Magazines
  • Scissors
Take the Case: Chain of Evidence


To explore how scientists can bring information, insights, and analytical skills to bear on matters of public concern by examining how forensic science helps to solve crimes.


Scientists today make a living in many more scientific disciplines than in the past 100 years. Students may believe that science influences technology, but they may not realize that technology also influences science. New scientific/technological advances that help forensic scientists solve more complicated crimes are constantly being developed, and in the process, new disciplines of forensic sciences are unfolding. Some new technologies are helping scientists solve crimes from millions of years ago.

Students may believe that crime fiction television shows like “CSI” and “Law and Order” are true depictions of how crimes are solved, but that is not the case. Most crime scene investigators (CSIs), or forensic scientists, spend more hours in the lab studying evidence than tracking down criminals. Forensic scientists also form wide research circles with scientists from other disciplines who can lend special expertise to solving a crime. In fact, it is rare for a forensic scientist to solve a crime without the expertise of scientists from other forensic science disciplines.

Forensic scientists do not enforce the law. Their role is to form an unbiased look at crime scene evidence and information and determine the facts that lead to the truth. They are usually involved in all aspects of a case, and the conclusions their investigations bring to a case serve the defense, the prosecution, and the courts. Their role is to uncover the truth through factual evidence and scientific expertise.

In this lesson, students will use the interactive Take the Case: Chain of Evidence, from the National Law Enforcement Museum, to investigate a crime scene, learn the basics about which tools are used when attempting to solve a case, learn how evidence is collected and analyzed, and learn how suspects and witnesses are interviewed. This lesson is most appropriate for students in grades 8  through 10.


It can be difficult for witnesses of a crime to remember accurately what they saw or heard, especially if the event happened in a stressful, fast-moving situation. This activity will test students’ ability to remember what they see.

Before doing this activity with the students, look through some magazines to find pictures of different faces. You’ll need eight to twelve different faces. Look for ones that are about the same size. Cut the faces out and then cut the facial features into different pieces, i.e., the eyes, mouth, nose, brow, hair, etc. Mix the pieces all together and then divide the pieces into several piles. You will ask the students to pair up for this activity, which will test their ability to remember what they see, and you’ll want one pile of several faces for each pair of students.

Working in pairs, one student constructs a face from the features. The second student then has 10 seconds to memorize it. When the 10 seconds are up, the first student should pull aside the pieces and write the second student’s initials on the back of each piece and then put the pieces back into the pile and mix them up. Then the second student should try to reconstruct that same face again without looking at the initials on the back of the pieces. The first student will observe and note how close the second student came to remembering the face.

Next, have each pair of students move to a different pile of features where the other student gets to construct a face. Once everyone has had a chance at this exercise, lead the class in a discussion about what they experienced when trying to remember what they saw. Use these questions to help you lead the discussion:

  • How many of you were able to correctly reconstruct a face?
  • Were you surprised that you could or could not do it?
  • What does that tell you about your ability to remember what you observe?

(Answers will vary. Encourage students to explain their answers.)

Now ask students to pair off again and repeat the exercise. Make sure they are working with different piles and a different student. But this time, limit to five seconds the time they have to memorize the faces. Try to do something that distracts them during these five seconds, such as rushing around the room or talking out loud—anything you can think of that will distract them.

When each student has had a chance to do the exercise, gather the class back together to encourage the students to talk about what was different about the second exercise. Ask:

  • How confident are you that you could witness an incident and accurately report what you saw?
  • Have you ever been in a situation where you were asked to recall the details of what occurred? How did you feel after reporting what you remember seeing?

(Answers may vary. Encourage students to explain their answers.)



Before students open the Take the Case: Chaine of Evidence interactive, they should use their Take the Case student esheet to research the role of a forensic scientist and research the answers to these questions:

  • What is forensic science (or CSI)?
    (It is any science used in public, a court, or in the justice system. It is any science used for the purposes of the law.)
  • What is evidence? Can you give an example?
    (Evidence is any material or information gathered from a crime scene or other location and is determined to be relevant to an investigation.)
  • Why is it important to preserve or record a crime scene?
    (It is important to make sure no evidence is contaminated and all relevant evidence is collected.)
  • What are the 10 areas of forensic science?
    (The 10 areas are: criminalists, digital and multimedia, engineering, general jurisprudence, odontology [dental], pathology/biology, physical anthropology, psychiatry/behavioral, questioned documents, and toxicology. See the Forensic Sciences Foundation for details about each area.)

Students should use their Take the Case student sheet to record their answers to these questions.

Next, ask the students to use their esheet to go to the interactive and begin investigating the crime scene. Students should work in small groups of up to three students to go through the interactive. One student could focus on collecting the evidence and recording the information on the Crime Scene Evidence student sheet (you can find answers to the questions on the Crime Scene Evidence teacher sheet). One student could then focus on the crime lab and recording the information from there on the Crime Lab Evidence student sheet. Finally, one student could focus on interviewing the witnesses. For this part, students can use the Interview Suspects part of the interactive to gather all of the relevant testimony and keep it in one place.

Once the students have gone through the interactive, they should come back together and use the evidence they’ve gathered to select the suspect(s) they believe are guilty of committing the crime.


To assess student understanding of how forensic science works in real life, ask them to answer these questions using their Take the Case student sheet and then discuss them in class:

  • What evidence led you to solve your case?
  • What other areas of forensic science would have been helpful in solving this case?
  • How could these scientists’ expertise have helped solve the case?
  • How does the process of solving a case in this interactive differ from the TV crime shows you have watched?

(Answers will vary. Encourage students to explain their answers.)


Hair Color Forensics discusses how forensic scientists can predict a suspect’s hair color by examining their DNA.

National Law Enforcement Museum Artifact Detective, from the NLEM, has listed a few of the more than 15,000 artifacts from the museum and is requesting help on uncovering the stories behind them. Students could choose an artifact and conduct research to see if they can solve the mystery.

Forensic Science Lesson Plans has many lesson plans and exercises to teach students about crime scenes and the different kinds of evidence that can be collected. It goes into depth about evidence such as blood samples and DNA.

At Forensic Science, students can learn more about different areas of crime investigation, such as computer and email crimes, tools for conducting an autopsy, murder weapons, etc. It also features an interactive with crossword puzzles, quizzes, and interviews with forensic scientists.

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Lesson Details

Grades Themes Type Project 2061 Benchmarks National Science Standards