OVERVIEW

Activity Overview:

Students will work together (in teams of 4) as forensic scientists to solve the crime of “Who broke into our school and stole all the tablets?” Students will compare DNA samples from three suspects to DNA taken from a hair left at the crime scene. From their comparisons they will draw conclusions to identify a suspect. Once the suspect is identified, they will present their findings and rationale to the class

Meta description

• Subject Area: Computer Science, Science, Engineering
• Grade Level : 6-8
• Computer Science Domains:
  • Networks and The Internet, Data Analysis
• Computer Science Principles:
  • Fostering an Inclusive Computing Culture, Collaborating Around Computing
• Materials:
  • Website, unplugged
• Considerations: +

Lesson Plan

Overview

Students will work together (in teams of 4) as forensic scientists to solve the crime of “Who broke into our school and stole all the tablets?” Students will compare DNA samples from three suspects to DNA taken from a hair left at the crime scene. From their comparisons they will draw conclusions to identify a suspect. Once the suspect is identified, they will present their findings and rationale to the class

ASSESSMENT PRE/POST-TEST

Pre-Questions Explain what DNA is in your own words. Why is DNA important in solving crimes? What did we use before DNA? How has the use of DNA in investigations improved the rate of crimes being solved? Post Questions How did DNA sequencing help you solve this crime? Could you have done this without DNA (or the strand of hair)? Do you think the use of DNA in crime solving has improved the accuracy of solving crimes and imprisioning the correct person?

OBJECTIVES

Describe the organization of DNA into repeating nucleotide base pair sequences (prior to beginning this project students should be well-versed in DNA and nucleotide sequences) Explain how DNA profiling is used to link people to crime and paternity cases (done in preparing for lesson, in lesson readings, and class discussion & presentations) Describe the role of biomedical engineering in DNA profiling (done in preparing for lesson, in lesson readings, and class discussion)

CATCH/HOOK

Lesson ‘Hook”: Doors to the tablets and laptops cabinent will be open at the beginning of class, but only FOUR laptops will be left. Where did the devices go? Oh no! We’ve been robbed! Students will have to do a survey of the room. Find clues-what did the perpetrator leave behind? Where did they come in? What else did they take? On the SmartBoard screen we will show a picture of a single hair supposedly left by the criminal. A link to the CODIS website will be next. Students will be in their teams (groups/tables of 4) and the class will discuss CODIS, review nucleotide base pairs and plan how their team will review the little information left by the ciminal mastermind.

ACTIVITY INSTRUCTIONS

Procedure Whole Class Discussion-Background Information In this activity, probability is used to determine which suspect is the most likely match. We are told that the likelihood of a random match between a CODIS site for one person and someone else is 1/10. Why is that? Each of the regions that we are considering here contains an allele, or, a version of a gene. Which allele you have at a particular site is determined by your parents’ genetic data and meiosis, as well as any errors in replication. However, these alleles are not unique in a population; you can have the same allele as someone else. Statisticians study populations to get an idea about the distribution of alleles (how many people have each kind of allele). In this way, statisticians can estimate a probability that any two people have the same allele. If the likelihood of a CODIS site match between two random people was much greater or much less than the 1/10 used in this activity, the number of matches we would need in order to be reasonably certain of the suspect’s guilt would also change. Teacher Duty/Task-Before the Activity Make copies of the Suspect CODIS Analysis Worksheet, one per team/group Set the stage for the activity Hide/Remove most devices Create slideshow of project to guide students Conducting the Introduction/Motivation section Provide notes/template for SPED students During Lesson-With the Students Divide the class into pairs of students, and pass out a worksheet to each team. Assist students as they complete their worksheets. Have teams conclude by writing on their worksheets which suspect their DNA profiling implicates in the robbery. Have the teams with the correct answer describe how they arrived at their conclusion. (Answer: Suspect 2 seems likely based on a match with four CODIS sites). Have students calculate the likelihood that suspect 2, even though he matches four CODIS sites, is not the owner of the hair in the bank robber’s glove. (Answer: (1/10)4 = 1 in 10,000, not good enough – need more CODIS site data) Have students act as biomedical engineers and analyze the results of the DNA profiling for the police investigators as described in the post-assessment activity.

Supplements

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REVIEW

Presentations from each team, whole class discussion, final submission of worksheet and presentation

STANDARDS