Inquiry Learning about DNA through the World of CSI Forensics in Education - Welcome to the fascinating interface between inquiry learning and forensic science. According to a survey by the National Science Teachers Association (NSTA), the use of forensic science investigative scenarios that use such criminalistic techniques as DNA profiling has become a very hottest trend in science teaching. In fact, 77 percent of 450 middle and high school science educators who responded to a recent survey, indicated that one or more teachers in their school or school district were using forensic investigations to teach science. Driving this, of course, has been the broad popularity of forensic-based TV shows. According to NSTA President Anne Tweed, TV shows like Crime Scene Investigation (CSI) and Forensic Files resonate especially well with students at the middle and high school levels. Science teachers, in turn, are taking advantage of this interest by using it to boost student excitement about science learning. The use of forensic science in the classroom may take different forms. Some teachers integrate lessons into existing science classes while others offer separate forensic science courses for students. This is also evident from the comments of teachers themselves. One such teacher said of her own experience with forensics, "My kids are enthralled when we do forensics in class. I usually conduct two major units each year! They love the scientific testing, the thinking, and the conclusions they reach. They love the feel of being 'real' scientists." Curricular Resources - The limited availability of good forensic science lessons, however, has made it difficult for many teachers to maximize the potential benefit of incorporating forensic exercises into their curricula. In an effort to better meet teacher needs, the NSTA has partnered with Court TV and the American Academy of Forensic Science to develop curriculum units on forensic science for middle and high school students. This collaborative effort now provides free standards-based forensic science curriculum for high school science teachers which can be downloaded at www.courttv.com/forensics_curriculum. Today’s Exercise - The forensic exercise that has been developed for this professional development workshop is intended for instructors who seek to take advantage of student interest in forensic science as a vehicle for meaningful inquiry learning. The specific investigative scenarios are geared toward you as instructors and are intended to illustrate the type of inquiry learning that can take place using a forensic context. In your own classroom, this approach to teaching can be customized in an age-appropriate manner to achieve a broad range of teaching objectives. These could include exposing students to scientific laboratory methods, exposing students to the significance of physical evidence, encouraging electronic searching methods, developing writing and speaking skills, encouraging inquiry and cooperative learning, illustrating the practical application of such mathematical principles as statistics and probability, demonstrating biological principles like genetic diversity and inheritance. In today’s exercise you will be presented with a collection of evidentiary material from a series of criminal investigations. One of the fundamental principles of criminal investigations is that victims and perpetrators usually leave some trace of themselves at the scene of a crime. It is the task of the criminalist to find this “trace” evidence and to use it to shed insight on the crime and the explanations offered by the persons involved. Most recently DNA has become one of the most important types of “trace” evidence. By using forensic DNA as part of an inquiry-based educational activity, you will be able to explore some of the fundamental of human genetics and diversity. Procedures - (1) Examine one of the sets of evidentiary material associated with a crime scene investigation and provide a careful description of the individual pieces of evidence. (2) On the evidence form provided, Make careful note of anything that you think might be of value to you in investigating the crime. Make sure that you note possible locations on the evidence where there may be trace biological evidence left by a victim or a perpetrator. (3) Develop and write down a scenario of the crime. Make note of what person’s DNA (victim or perpetrator) might be on the various pieces of evidence according to your scenario. (4) Collect the potential DNA evidence as a police evidence technician would. To do this, obtain a cotton swab and a tube of water. (5) Label the tube of water with the same number as the evidence. If you are going to take more than one DNA sample from a single piece of evidence, label each tube with the evidence number followed by a dash and then a second number starting with 1. (For example if you took two samples from evidence item #17 you would label your tubes 17-1 and 17-2) (6) When you are ready to collect the evidence, dip the cotton swab in the tube of water. Save the tube with the remaining water. Dab the spot on the evidence from which you hope to collect DNA with the wet cotton swab. (7) Rub the cotton swab back and forth over the area from which you want to collect DNA. (8) Return the cotton swab to the tube of water and shake/twirl it back and forth in the tube to release the DNA. (9) Throw away the cotton swab and save the tube for DNA testing by the instructor. Please make sure that the tube is properly labeled with the evidence number. (10) Discuss the results of the DNA testing with your peers. How do the results fit your hypotheses about the crime. Do you need to revise your hypotheses? Discuss what else you have observed. Your instructor will help facilitate these discussions. Crime Scene Investigation #1 You have recovered the following in connection with a criminal investigation: (A) A screwdriver which may have been used as a weapon was found in a back alley dumpster near the spot where a murder victim was found. (B) A can of Mountain Dew was found in the victim’s apartment. (C) An envelope containing a typed death threat letter was found in the victim’s apartment. Your suspect in this investigation claims not to know the victim and not to have sent any threatening letters to the victim. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Can DNA fingerprinting tell you if your suspect telling the truth? Crime Scene Investigation #2 You have recovered the following in connection with a criminal investigation: (A) A socket wrench which may have been used as a weapon was found near the body of a murder victim. (B) A pair of latex gloves was found in the cab of the pickup truck that is owned by the son of the murder victim. The victim’s son has been taken to police headquarters for questioning about the murder. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Can DNA fingerprinting implicate the son as the prime suspect in this investigation? Crime Scene Investigation #3 You have recovered the following in connection with a criminal investigation: (A) A Coke can was found 3 feet away from the body of a murder victim. The victim was found in a large public park by a gardener who works there. (B) A box cutter which may have been used as a weapon was found near the victim’s body. The victim was last seen walking near the park with her roommate. During questioning the roommate claims that she know nothing about the crime. She was however surprised to see that the police had found her box cutter. She mentions that she accidentally cut herself while using the box cutter at school several days earlier. The roommate also claimed that she lost the box cutter sometime after her injury. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Can DNA fingerprinting help you to accept or reject the roommate’s story in this investigation? Crime Scene Investigation #4 You have recovered the following in connection with a criminal investigation: (A) A piece of the tile flooring removed from washroom of the victim’ home that has a couple of drops of blood. (B) A knife which may have been used as a weapon was found in the garage a few feet away from the victim’s body. One of the neighbors informs police that the victim’s father had gotten into a major fight earlier in the day. The current whereabouts of the father are unknown. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Can the DNA fingerprints help you to decide whether or not to consider the father to be a suspect? Crime Scene Investigation #5 You have recovered the following in connection with a criminal investigation: (A) A piece of broken window glass from the back door of the victim’s home. (B) A telephone cord that may have been used to strangle the victim. This may be a case of burglary and murder. Your prime suspect admits that he is guilty of breaking and entering. He claims that he cut himself by accident during the break in. However, he also claims that the homeowner was alive when he left. Your prime suspect suggests that another person came later and committed the murder. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Do you believe the suspect’s explanation? (Note blood pattern evidence on glass i.e., drop on print) Crime Scene Investigation #6 You have recovered the following in connection with a criminal investigation: (A) A metal chain which may have been used as a weapon was found in a trash can at a highway rest stop 2 miles away from where the victim was discovered in an abandoned car. (B) A bottle was found in another trash can at a campsite where your prime suspect was discovered and arrested. Your suspect claims that he has no connection to the bottle, the chains, or the murder. What trace of the victim or suspect might be found on the evidence? What might DNA fingerprinting tell you about this case? Can DNA fingerprinting help you to decide if the suspect is telling the truth?
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