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POD: Would fibers be physical or biological evidence? WotD: Amorphous
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Video: Cold Case Files Volume 1 “One Night on the Bayou”
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Exit Ticket: Complete the 4 post video questions Homework: Complete questions for homework
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POD: How are fibers used in crime scenes? WotD: Crystalline
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Fiber evidence can be useful to identify or exclude suspects as either physical or biological evidence.
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Identify and describe common weave patterns of textile samples Compare and contrast various types of fibers through physical and chemical analysis Describe principle characteristics used to identify common fibers Apply forensic science techniques to analyze fibers
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Exit Ticket: How soon do fibers need to be collected at a crime scene? Homework: Go to http://www.crime-scene- investigator.net/dont-forget-those- standards.htmlhttp://www.crime-scene- investigator.net/dont-forget-those- standards.html For each of the evidence types identify the quantity and type of samples collected from a known source.
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POD: Why are fibers considered trace evidence? WotD: Direct transfer
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Exit Ticket: In the process of normal activity we shed fibers and pick up fibers. Explain how these two facts can help determine what occurred at a crime scene. Homework: Complete the Book quest through using Google for any questions that you were unable to complete.
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POD: How can fibers be used to solve a murder case? WotD: Fiber
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Read the case and answer the question on the Jeffrey MacDonald’s case.
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Exit Ticket: Journal Prompt for Article Review Homework: Find a case that used fibers and write a one paragraph summary.
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POD: List the 5 ways that fiber evidence evaluation can be used to solve a case. WotD: Mineral fiber
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What case did you find? Who was guilty? What was the outcome of the case?
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Complete the second side of the Hair/Fiber Microscope lab. Analyze the six fibers
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Exit Ticket: What is the most common form of fiber transfer to cause fiber evidence to be at a crime scene? Homework: Journal Prompt #2 Lab Review. Complete for both parts of the lab, hair and fibers.
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POD: Two common lab techniques to analyze fibers located at a crime scene are Microscopes and Infrared Spectroscopy. Describe the physical and chemical differences between these two techniques. WotD: Monomer
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Use the textbook to follow the lab instructions Record the data on the data table
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Exit Ticket: What percentage of fibers are lost within the first 24 hours? Homework: Complete the post lab questions and the lab journal prompt
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POD: There are three main destructive fiber analysis; burning test, dissolving test, and dye test. What does it mean to be a destructive test? WotD: Natural fiber
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Use the textbook to follow the lab instructions Record the data on the data table
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Exit Ticket: List 3 things that are revealed by using a microscope for fiber analysis. Homework: Complete the post lab questions and further research on fibers.
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POD: Describe the difference between Warp and Weft. Do all fibers have both? WotD: Polymer
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Use the textbook to follow the lab instructions Record the data on the data table
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Exit Ticket: Hair made of proteins such as wool, cashmere, mohair, angora, and silk, come from what type of fibers? Homework: Complete the post lab questions.
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POD: List the three types of natural fibers. WotD: Secondary transfer
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Use a sample large enough to determine if the fabric or fiber will continue to burn or die out quickly. Hold the fiber or fabric with a forceps. Try to hold the fabric parallel to the table so that the flames will move across the fabric or fiber. If you hold the fabric so that the fabric is suspended, the flames will engulf the entire fabric at once. This makes it difficult to determine if the fabric continues to burn after being held in the flame, or if the flames die out. Hold the fabric in the flame for 3 seconds to ensure that the fabric is ignited. To detect the odor of the smoke, it is important to check immediately after the fabric is ignited. You will most likely see a small amount of smoke that disappears quickly. Note how the synthetic fabrics appear to melt and may look bubbly as they burn.
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Exit Ticket: Complete the Lab Journal Prompt Homework: Answer the Post lab questions.
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POD: What percentage of fibers are produced synthetically? What does it mean for a fiber to be produced synthetically? WotD: Synthetic fiber
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Read the lab Place your fiber strips in each dye Return to your seats.
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Identify the following natural fibers as Animal, Plant, or Mineral: Wool Fiberglass Hemp Cotton Silk Angora Asbestos Jute Cashmere Flax Alpaca
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Pull Fabric strips out of the dye Rinse with cold water Pat dry with a paper towel Fill in the data table Compare the unknown samples to the known colors Answer the post lab questions
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Exit Ticket: List 2 advantages and 2 disadvantages of using Plant fibers. Homework: Finish post lab questions and complete the journal prompt on lab
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POD: List the 2 types of Synthetic fibers and give an example of each. WotD: Textile
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Exit Ticket: Can a suspect truly destroy or remove ALL evidence? Homework: Complete the essay on crime scenes and burned fiber evidence.
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POD: Summarize the Unit in 6 points WotD: Warp and Weft
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Fibers are a form of class evidence. Fibers are a form of trace evidence. Fibers are spun into yarns having specific characteristics. Yarns are woven, with different patterns, into clothing or textiles. Fiber evidence is gathered using different techniques.
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Fibers are analyzed using burn tests, tests for solubility in different solutions, polarized light microscopy, or infrared spectroscopy. Fibers are classified as natural or synthetic. Natural fiber sources include: Animal hair Plant seeds, fruit, stems, or leaves Minerals.
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Read Cases and complete the “think critically” Read the “Careers in Forensics” for Fibers and complete the Journal Prompt for Article Review. Complete the end of Chapter Review
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Unit 4 Test: Fibers Case Study: Read the case and summarize the case focusing on the types of evidence used to solve the case.
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Exit Ticket: What careers use forensic science? Homework: Finish the review and study for the test. Folder for Units 3 & 4 are due tomorrow.
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