Project-Based Learning (PBL)

Not Guilty: Students Discover How Science Can Free the Innocent

A biology-class project teaches high school students about the real-life application of DNA testing in wrongful-conviction cases.

May 5, 2008

For eighteen years, Dennis Williams was imprisoned for crimes he didn't commit. Then, while incarcerated on Illinois's death row in a cell located just steps from the electric chair, DNA tests helped prove his innocence. He was released from prison in 1996.

At Mandarin High School, in Jacksonville, Florida, exploring wrongful convictions of people such as Dennis Williams has become part of a biology-class project that illustrates the crucial role science plays in our everyday lives. The project calls for students to research a specific incident of wrongful conviction and give a presentation that illustrates the role DNA evidence played as a crime-solving tool in the case.

Mandarin teacher Diane Wagers has used this project in her second-year biology class for six years, and she says many of her students become angry when they first learn about wrongful imprisonment. "They literally will jump out of their seats and ask, 'Why did this happen?'" Wagers says. Getting to the bottom of why innocent people are convicted, she notes, both motivates her students to learn about DNA testing and illustrates the practical application of the biological sciences.

Wagers makes the project part of her biology curriculum because she believes connecting science concepts to life outside of the classroom is essential to good teaching. "Biology is the study of life, and when students look at these issues of wrongful conviction, it comes alive for them," she explains. "It helps them remember what they've learned, because they see it is real."

Student Britney Schank agrees. "In every other class, you just learn about DNA, its structure, how it's built, and all the boring stuff," Shank says. The DNA-testing project, however, showed her more. "I saw how DNA affects people's lives and how it comes into play."

Introducing the Innocence Project

At the beginning of the assignment, Wagers conducts a mini-lesson on DNA and its uses, including the ways people employ it in criminal investigations. Although her Biology II students have a background knowledge of DNA, Wagers says it's often helpful to revisit basic concepts.

After the refresher on the subject, students choose to either work alone or with a partner to research the legal case of someone who has been exonerated by DNA testing. Wagers says she gives students the option to work with a partner because it promotes teamwork and allows students to collaborate with someone who may have strengths different from their own.

To get her students started on the research portion of the assignment, Wagers points them to the nonprofit Innocence Project, which lists nearly 200 case profiles online. Each profile provides a case summary and links to additional information about the common causes of wrongful convictions, such as the unreliable and limited science used prior to the advent of DNA testing. The site also features an archive of audio and video clips that includes interviews with some of the people who've been exonerated.

As the students work, Wagers circulates around the room to ask questions and make sure they understand the science behind DNA testing. "When you go from group to group, you can sit right down and look at a kid and ask, 'Do you get this?'" Wagers explains. "You can tell right then whether they comprehend it." If Wagers believes a student lacks a clear understanding of the science, she provides him or her with additional instruction or invites the student to come in after school. If a number of students seem confused, she'll review concepts with the entire class or refer them to online tutorials such as those created by the Dolan DNA Learning Center. Students also tutor one another.

Presenting the Facts

After an initial in-class work session, Wagers gives students two weeks outside of class to collect information on their case, organize the facts into a Microsoft PowerPoint presentation (Wagers provides an outline), and prepare a discussion of the role DNA played in the exoneration they studied.

During the class presentations, Wagers grades students according to their understanding of DNA and its relevance to the case they researched, as well as the overall quality of their presentation. (Download a PDF of her grading rubric.) Students who worked in pairs must make a presentation together, and both members need to be able to answer follow-up questions.

At the close of the project, Wagers holds a debriefing discussion (see "Diving into DNA: Content and Context" below for topic ideas). For example, Wagers will ask students to talk about the cases they profiled and discuss whether they think DNA testing in criminal cases should receive public funding. Wagers says these conversations bring out a variety of responses from the students.

For some, the power of DNA testing makes a big impression: Several students jokingly tell Wagers they will never commit a crime now because, with DNA testing, they know they'll get caught. Others truly take the lesson to heart. For instance, one of Wagers's students has contacted the Innocence Project to help a relative he feels was wrongfully convicted. "He is taking something we've studied and putting it to use," Wagers says.

Diving into DNA: Content and Context

When replicating this project on DNA testing and wrongful convictions, maximize the experience for students by providing them with information usually considered outside the realm of a science class. Here are some suggestions from biology teacher Diane Wagers:

Know the Content

Most biology teachers have a solid grasp of DNA, but not everyone understands how investigators might use it in a criminal investigation. Wagers suggests teachers familiarize themselves with the ways investigators find DNA at a crime scene and with the various kinds of DNA tests they use. Wagers also visited a local crime lab in order to better understand how technicians do DNA testing in the real world. Also, the U.S. Justice Department's National Criminal Justice Reference Service provides a thorough primer on DNA evidence. (Download the PDF.)

Teach the History

To help students comprehend how someone could go to prison for a crime he or she didn't commit, provide a proper historical context for forensic science. Students need to understand, for example, that DNA testing is a relatively new innovation that hasn't always been available to investigators. Furthermore, in some cases, there is simply no DNA evidence to test. The Innocence Project provides a good summary of the weaknesses of forensic science prior to the widespread adoption of DNA testing, including less-reliable tests involving serology and hair comparisons.

Discuss the Economics

Although DNA testing is highly effective, because of its high cost, those involved in criminal investigations do not always use it. Explain which local government agencies conduct DNA testing, how much it costs, and how long the process takes. Discuss with students the barriers to using DNA testing, and ask them to propose possible solutions.

Explore the Ethics

Because DNA testing has been such a successful tool in both exonerating and implicating suspects, some policy makers have suggested creating a DNA database for everyone living in the United States. Proponents of the database argue that police could immediately run DNA gathered from a crime scene through the database and quickly identify and arrest a suspect. Discuss how people could misuse such a database, and ask why some ethnic groups might oppose this type of resource.

Respond to Different Learning Needs

For students who are uncomfortable with public speaking or who may not have access to a computer, the Internet, or PowerPoint, Wagers provides alternative assignments that also meet state curriculum standards. One alternative is to ask students to read The Innocent Man, by John Grisham, and then meet after school for a book club-style discussion. Wagers also allows students to meet after school to watch the documentary After Innocence and then tests them on the contents of the film.

Work with Mature Students

Because of the mature nature of some of the crimes classes will encounter in their research, Wagers recommends assigning the DNA-testing project to students who are at least sixteen years old.

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