Time for our next unit… • http://www.youtube.com/watch?v=7WseRJMQf1U
Forensic Science – “How can science solve crime?” Expected Learning: to introduce our Forensic science unit – “how can science solve crime?
Getting started • On the next blank page in your books, write the heading “Forensic Science – how can science solve crime?” • Draw the table below and make it fill the WHOLE page • Each lesson you should fill in the table to help keep track of what you have done and help you study for tests
What is the main reason the police secure a crime scene? • A – To stop people minding other people’s business and gossiping • B – To protect eh public from being harmed by anything lying around the crime scene • C – To ensure that vital evidence is not altered or destroyed • D – To stop people from seeing something that might distress them
Which statement about fingerprints is false? • A -Identical twins are the only people who have the same fingerprints • B – Fingerprints consist of perspiration and oils • C – Fingerprints can be detected by dusting fine powders onto areas people touch • D – Magnetic powders can help lift fingerprints off plastic bags
Which of these separation techniques can quickly help determine which brand of pen a suspect used? • A – Filtration • B – Distillation • C – Paper Chromatography • D - Centrifuging
What is the principle by which every forensic scientist works? • A – Every culprit will be caught sooner or later • B – Every contact leaves a trace • C – Every piece of evidence tells a story • D – The more evidence you find, the greater the chance of solving the crime
Everyone who witnesses a crime will be able to provide the same description of what occurred? • A – True • B - False
A forensic scientist’s job is to solve crime • A – True • B - False
The slight indentations that form on one sheet of paper that is underneath another that you are writing on are sometimes called imprints • A – True • B - False
Used chewing gum can provide useful evidence at a crime scene • A – True • B - False
Answers: • C • A • C • B • B • B • A • A • Tally your answer out of 8.
Prior-knowledge Activity • On a piece of paper, write down your answers to the following question: • List all the words you can think of to do with “crime” • What does a forensic scientist do? • OR • Have a class discussion about the following two questions: • What is crime? • What are some examples of crime? • What does a forensic scientist do?
Key terms • Crime – an act committed in violation of a lab forbidding it for which punishment is imposed upon conviction. There are lots of different kinds of crime. • Can you think of some different types of crime? • Forensic scientist – scientist who solves problems such as what caused an accident or who committed a crime
What I think now… • Write down your current answer to the question – • “How can science solve crime?” • We’ll revisit your answer at the end of the unit, so make sure you keep it safe and don’t lose or swap books!
Crime scenes • After a crime has occurred, police and forensic scientists investigate the crime scene and gather evidence. • Evidence is objects found at a crime scene or statements by witnesses to a crime. • Witness statements need to be treated very carefully as people’s memories can be affected by events or time. They have misheard a conversation or they may have heard the information from someone else
Whispers • What to do: • Get everyone in the class to stand in one straight line. The teacher will whisper some information into the ear of the person standing at the front of the line. This person will then whisper the information into the ear of the next person and so on. When the information gets to the end of the line, compare the initial whisper with the final whisper.
Whispers – What did you discover? • 1. What sentence did the teacher whisper? • 2. What was the whispered sentence at the end? • 3. If there was a difference, explain why the difference occurred between the two sentences. • 4. Why do police need to treat people’s memory of an event or conversation very carefully?
Being an eyewitness • An eyewitness is someone who witnesses a crime. Sometimes the crime happens so quickly and so unexpectedly that you do not have time to see what is going on, let alone take it in. Several eyewitnesses wh0o witness the same crime sometimes have very different stories to tell.
Being an eyewitness • Look at the image on the following slide for 10 seconds, then try and answer the questions that follow.
Being an eyewitness • Which window has been smashed? • What colour are the computers? • What is the colour of the coat hanging on the back of the chair? • What is the colour of the soft drink can next to the computer? • What is written on the note lying on the keyboard? • How many computers can you see? • How many students are looking through the broken window and are they male or female?
Being an eyewitness • How many questions did you get right? Compare your results with those of the rest of the class. • How observant were you? How good an eyewitness would you make? • Did anyone in the class answer all the questions correctly?
Being an eyewitness • How do you think you would perform on these questions if you had looked at the picture for ten seconds yesterday? Use your response to explain why police ask everyone that was near the scene of a crime what they saw as soon as possible after the crime has taken place. • Why is it best to have as many eyewitnesses as possible?
Reflection • What are you looking forward to in this unit? • How did you go in the pre-quiz? Write down your score. • Write down one goal for this unit. How can you attempt to reach that goal?
Lesson 2 – Forensic Scientists and Collecting evidence Expected learning: to learn about some of the different types of physical evidence that can be used to solve crime
Enter the forensic scientist • The principal by which forensic scientists work by is that every contact leaves a trace or evidence • There are many kinds of evidence that can be left behind at crime scenes
What evidence would you collect? Mock Crime Scene: http://www.masss.gov
Fingerprints • When we touch objects we leave fingerprints, the pattern of tiny ridges in the skin on the tips of our fingers • This is because small amounts of perspiration and oil are on our skin at all times. This small amount of moisture deposits in the pattern of the ridges when we touch something
Fingerprints • Amazingly, every person’s fingerprints are unique – even identical twins have different fingerprints. This makes fingerprints a vital piece of evidence because they can place a suspect at the scene of a crime
Fingerprints • When fingerprints are left at the scene of a crime, fine powder is dusted softly onto them so that the powder sticks to the traces of sweat and oil. Photos are taken and then the prints are lifted off the surface with tape
Fingerprints • Fingerprints found at crime scenes are checked using the Automatic Fingerprint Identification System (AFIS) in case the culprits fingerprints are already on file. This computerised system very quickly compares crime scene fingerprints with a computer database of the fingerprints of known offenders
Taking your own prints • Roll your fingers one at a time across the inkpad • Carefully roll your finger across the Fingerprint worksheet in each box • Wipe each finger clean after making each fingerprint • Compare your prints with those of other students in the class • Complete the questions on the fingerprint worksheet • Make sure you keep your fingerprint profile as you will need this in a future lesson
Fingerprints in court • Fingerprints have not always been used as evidence in court. When they were first used, the defence lawyers objected because the have never been used before. The judge sent he fingerprint expert out of the room and the jury were fingerprinted. The expert was able to accurately lift a print of a juror off an object and correctly name the juror who had put it there. The judge allowed the fingerprints to be used as evidence
WOW – Lip Prints • The prints left by someone’s lips on a glass or cup can also be used to help identify who was present when a crime was committed. If the person was wearing lip gloss or lipstick, the brand can be identified with chemical testing.
Questions • Answer the questions on the following slide • Read through the information in Science Edge 2 Chapter 1 pages 2, 3, 4, 6, 7, 8, 9, 10 and answer the questions on page 34 • Add any new definitions to your code breaker sheet • During this time you will conference with your teacher for your next progress report.
Questions… • 1. Explain why we leave fingerprints on things. • 2. Describe how a fingerprint can be obtained from an object such as a glass • Handout Questions: • 1-5 and 7
Reflection • What were the most common fingerprint patterns in our class? • List two reasons why the role of a forensic scientist is important
Lesson 3 – Collecting evidence Expected Learning – to learn about some of the different types of physical evidence that can be used to solve crime
Imprints • A note pad was found at a crime scene. There was nothing written on it – or was there? • One simple way to reveal what was written on the previous page before it was removed from the notepad is to rub a very soft pencil over the top piece of paper. • This works because when we write on paper we put a lot of pressure on it with the end of the pen or pencil. The pressure can be transferred to the sheet below. • Even though the pressure on this second page is not as great, it can leave slight indentations in the paper. There are called imprints
Imprint Activity • You need – notepad, pen, soft pencil • What to do: • Write a secret message on the top sheet of the notepad using a pen. Do not let your partner see what you write! • Remove the top sheet and give the next sheet to your partner • Get your partner to gently shade over the imprint area with the soft pencil. Can he or she read the message? • Switch and do the same to discover your partner’s secret message • Stick the original message and the imprint into your workbook
Imprint Activity • What did you discover? • 1. What was the message that your partner wrote? • 2. How easy was it to work out the message? • 3. How might an imprint found at a crime scene help identify the person who committed the crime?
Fibres - Hairs & Fabric • Fibres from fabric and hair can be another type of evidence that can place a suspect at the scene of a crime. • The fibres may be found of the floor, on clothes or perhaps caught on a piece of furniture
Hair • Hair is made of a protein called keratin • The shape and texture of hair is influenced heavily by genes • Hair colour is mostly the result of pigments, which are chemical compounds that reflect certain wavelengths on visible light • In order to test hair for DNA (we’ll learn more about DNA in a few lessons time), the root must be present • Different characteristics of hair can help us identify what species that hair has come from
Medulla – central core(may be absent) Cortex – protein-rich structure around the medulla that contains pigment Hair Structure Hair is composed of three principal parts: Cuticle – outer coating composed of overlapping scales The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside. http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Fabric Fibres • A fibre is the smallest unit of a textile material • It is much longer than its diameter • Matching unique fibres found on the clothing of a victim to fibres on a suspect’s clothing can be very helpful in an investigation, whereas the matching of common fibres such as white cotton or blue denim would be less useful • The discovery of multiple fibres transferred between the victim and suspect increases the likelihood that these two individuals had contact.
Analysing Fibres • Different kinds of microscopes are used to identify and compare fibres. Microscopes can identify if a hair is from a person or an animal, if a fibre is from carpet or clothing, if the fibre has been cut and, if so, by what type of cutting tool. Forensic scientists can even match up fibres found at the scene of the crime with those from a suspect’s house
Analysing Fibres Prac • You will have a chance to examine some different hair and fibre samples. • If you do not wish to look at your own hair, you can use another sample