Forensic science v456

Forensic science v456

Forensic science

Introduction

The subject of this lesson is 'Facts and figures'.

iscuss with a classmate the following questions:

  • What do you know about forensic science?
  • Do you know how long people have been using fingerprint in crime scenes?

In the 1890s Francis Dalton wrote about fingerprints and proved that each person has a unique print that stays the same all their life. Argentina was the first country in the world to use fingerprinting in criminal cases and in 1904 the New York City police force began collecting fingerprints of criminals. In 1910 in France, the first crime lab opened, and it used scientific techniques to examine evidence.

This lesson contains 3 steps and an evaluation.
Work them through step by step.

Step Activity  

 

Introduction

Find out what you already know.

Step 1

Speaking (and reading)

Make a list with your classmate about types of forensic evidence etc. Complete the chart. Read a text about trace evidence. Answer the questions.

Step 2

Reading (and watching)

Read the text. Do the exercise. Watch a video and answer questions: true or false. Complete the transcript.

Step 3

Grammar

Reported speech

Step 4

Task

Follow instructions and write your own crime report.

 

Evaluation

Reflecting on what you have learned.

 

Difficult words? Search these on Cambridge Dictionaries

Step 1 - Speaking

Speaking (and Reading)
What do you know about forensic evidence?
With your classmate, make a list of the following:

  • Different types of forensic evidence
  • How easy/difficult it is to collect
  • What school subjects would be useful to be a forensic scientist.

Would you like to be a forensic scientist? Why? Why not?


Do the exercise.

Read about trace evidence and hair.

Teaching Tip: Find out about Forensics

Almost every scientific field could be involved in forensics in some way. Here are just a few of the professionals who might work on a case: chemists, psychologists, pathologists (disease), botanists (plants), odontologists (teeth), entomologists (insects), and anthropologists (humans). So if you study forensics, you might use physics for comparing densities and investigating bullet impact; chemistry for identifying unknown substances, such as white powder that could be a drug; biology for identifying blood and DNA; and earth science for soil evidence.

The foundational principle of forensics is that a person always brings something to the crime scene and always leaves something. Often this is in the form of trace evidence: hair, fibre from clothing, chips of paint or glass, residue, and other "traces" of who was there. Hair evidence is examined in a lab under a compound microscope. Experts look at the colour and shape of hair, but they also find out what stage of growth the hair was at in order to determine how it was left behind. At the last stage, it might have been shed naturally. But if the hair was at an early stage, it might have been torn out by hard physical contact.

In cases of violent or suspicious deaths, a medical examiner looks at the victim. The examiner uses body temperature, the presence of bacteria, how digested the victim's food is, and other means to find out when the person died. He also looks for wounds or marks that suggest a struggle, and does an autopsy to examine the inside of the body as well. In cases where a death might be murder made to look like suicide, an investigator uses signs in the victim's body. In a drowning death, are there diatoms (microscopic water creatures) inside the body, from swallowing water? If so, do they match the diatoms found in the water where the body was? In the case of a burning, is there carbon monoxide, from smoke inhalation, in the bloodstream? If there is not, this would suggest that the person was already dead before the fire.

Identification is essential for getting the right suspect, but each victim has to be identified, too. In both cases, fingerprints, birthmarks, scars, tattoos, bones, and teeth can be used. Although fingerprinting is often useful for nailing down a suspect, not everyone has had his or her fingerprints recorded, and the police might not have access to someone's prints. One method that is more useful than fingerprinting is dental imprints. Teeth marks made by a criminal or teeth from a dead body can be used for accurate identification, even if only partial evidence is left. The teeth or bite marks are compared to dental records, especially X-rays. After the 1995 Oklahoma City bombing, dentists were able to identify about 25% of the victims based on teeth recovered from the site.

Prints All Over the Place
Collecting fingerprints is not that hard to do at home. Some fingerprints are visible - you can see marks left on a surface by dirty or oily fingers. Dusting is usually used for this type. Other prints are latent - you can't see them, but there are marks left by sweat and other organic residue from fingers. Fuming is often used for these.

If you have a magnifying glass, inspect your fingers. The unique patterns on your fingertips are caused by ridges in the dermis, the bottom layer of your skin. These patterns are fully developed in human beings just seven months after conception, while the fetus is still in the womb. The three typical patterns are loops, whorls, and arches. (Look at examples of different fingerprint patterns.) Your fingerprints are different than anyone else's, but did you know that fingerprint patterns tend to run in the family? If your fingerprints are a whorled pattern, one of your parents probably has a whorled pattern, too. It's just not exactly like yours!

To dust for fingerprints, sprinkle talcum powder or cornstarch on dark surfaces and cocoa powder on light surfaces (like the outside of a drinking glass) where there are visible prints. You can use a small paint or makeup brush with very soft bristles to gently swipe off the excess powder and leave the print. Use clear tape, sticky side down, to lift the print and then stick it to an opposite-coloured paper. What kinds of patterns do you see?

Who wrote it?
Chromatography is used to identify different inks. Say someone committed a crime by changing the dollar amount on a check. Using chromatography, an investigator could tell whether more than one ink pen was used to write on the check and whether the suspect's ink pen could have been used. How does it work? Well, ink is not really made up of one colour: there are actually different pigments making up one ink. In chromatography, the ink is soaked in a solution so that the different pigments will "bleed" apart and the true colours be revealed. (As you might guess, there is a drawback: the evidence is destroyed in the process.)

You can see how chromatography works by doing this experiment. Fill a tall glass halfway with water. Cut 3-4 strips of filter paper or of a heavy paper towel and attach the ends to a stiff piece of wire or a stick that can rest over the top of the glass. Next, make a large dot of ink about 1/2 an inch from the bottom of the strips, using a different brand of black marker, felt-tip pen, or ink pen for each strip. Set the strips in the glass so that the ends touch the water but the ink dots are above the water level. As the water soaks up into the paper, the ink will begin to separate into different colours. Note that some inks are not water-soluble; if the ink does not bleed, try using either nail polish remover or rubbing alcohol (stronger solvents that can dissolve the bonds in the ink) instead of water.

You can also look at "suspect" paper itself - are there watermarks or imprints from writing on top? Professionals also study handwriting and can analyse a sample of disguised writing to see if it has characteristics that match a suspect's normal writing.

Source: http://www.hometrainingtools.com/a/about-forensic-science-explorations-newsletter

 

Answer the questions.

  1. Think of situations where different kinds of hair - not just human - might be good clues.
  2. How might a medical examiner conclude that the person died before a fire?
  3. Why is fingerprinting not always possible to identify a suspect?
  4. Read here more about fingerprints: Fingerprint Analysis
  5. Take your own fingerprints. What type have you got?
  6. Read about chromatography. How reliable do you think it is? What are the disadvantages?

Discuss the answers with a classmate.

Step 2 - Reading and watching

Reading
Watch this video.

Do the exercise.

Read the text.

High fashion detective work
By Catriona Jenner Harvey.

Lipstick has many uses: it makes you look chic, adds color to an outfit, and — scientists have discovered — helps solve crimes.

In the same way as fingerprints are extracted from crime scenes and analyzed to provide clues about the perpetrator, experts are now discovering that they can do the same with lipstick. Although attempts have already been made to extract lipstick from surfaces, they have involved 'X-ray refraction' or 'Raman spectroscopy' and have been hugely time consuming, confusing, and costly.

But now experts are using 'gas chromatography' to help the process, according to Medical Daily. Apparently this involves adding an organic solvent to extract the oils and waxes from the lipstick, and then adding a basic organic solvent to remove any of the remaining residue. While the scientists at Western Illinois University, who are researching the matter, are currently just lifting samples from paper, they hope to extend this to all sorts of materials and surfaces from a crime scene in the future.

So there's a lesson to be learned here, one and all: Don't wear lipstick when you're off to commit a massive crime because chances are you'll get a smudge of it somewhere, and the feds will be right on your tail. Feels like there's a movie in there somewhere...

Source: http://www.seventeen.com

 

Do the exercises.

Watch and listen to the video again and complete the transcript in exercise 'transcript video' below.

Step 3 - Grammar

Let's look at ......reported speech.
When do we use reported speech? Sometimes someone says a sentence.
This we call a direct speech. For example:

We also can use the indirect/reported speech:
The federal justice minister said that throwing children or teenagers into prisons designed for adults made no sense.

We use reported speech (or indirect speech) when we say what someone said in the past: It makes no sense. ➨ He said it made no sense.

You can use that after the reporting verb. It doesn’t change the meaning:
He said it made no sense ➨ He said that it made no sense.

Change the tense!
When we report what someone said, we often put the main verb of the direct speech back one tense. Take a look at these examples:

Tense One tense back Direct speech Reported speech
1. present simple past simple I like milk. She said (that) she liked milk.
2. present continuous past continuous I am living in Amsterdam. She said (that) she was living in Amsterdam.
3. present perfect past perfect I haven't seen Masja. She said (that) she hadn't seen Masja.
4. past simple past perfect I bought a car. She said (that) she had bought a car OR She said (that) she bought a car.
5. will would 'll see you later. She said (that) she would see me later.
6. can could I can speak perfect English. She said (that) she could speak perfect English.

 

Change in pronoun!
You might also need to change the pronoun.
e.g.:
Direct speech: “I’ve visited London many times”, she said.
Reported speech: She said she had visited London many times.

Rewrite these sentences using reported speech.

  1. She said, ‘I play tennis every week”.
  2. They said, “We’re watching TV”.
  3. He said “I’ve finished my homework”.
  4. She said “I’ll help you, Mum!”
  5. Margie said “I can ride a bike”
  6. The team coach said ‘We won the last match and we’ll win the next one”.

Toets

Start

Step 4 - Task

Task
You are going to study a crime scene of your own.
Follow the instructions.

See how many clues you can identify in your own "crime scene". Choose a room (e.g., kitchen, living room, bedroom) or part of a room and go over it carefully, finding any trace evidence such as hair, clothing fibers, and chips of paint. You can collect these with a pair of tweezers and place them in envelopes or Ziplock bags to identify later. Are there any prints or scuff marks on the floor from shoes? Bits of soil or rock that might have been brought in?

To be thorough, record all of these clues. Make sketches in an investigation notebook if you want to. If you have a microscope, compare different kinds of hair at high power magnification. (You can also use a 10x or stronger magnifying glass.) Examine different cloth fibers, too - try cotton, wool, and rayon or acetate.

Make a wet mound of the hair or fibers by putting a drop of water on a microscope slide, adding the specimen, and pressing a cover slip down on top. What does each specimen look like? Is it smooth or rough? How do the ends look? Compare miscellaneous hair and fibers you pick up from the carpet or couch. Can you tell what kinds of fibers they are? Where did they likely come from? Are they all the same? Do you know who or what they belong(ed) to? Check out any dental evidence in your crime scene.

Then, if you have some willing suspects, make impressions of their bites and compare the
impressions to the evidence you found. A simple way to make impressions is to carefully
bite down into an apple or other soft food, but you can also bite into a folded sheet of white
paper with a piece of carbon paper inside. Be sure to get both back and front teeth in the bite impression.

Write up your crime scene report.


Click here to download your crime scene report.

 

Evaluation

Fill in this schedule and answer the questions below.

(Copy to Word or write down in your notebook)

Activity

 

Needs
Improvement

Satisfactory,
good

Excellent

 

Step 1 - Speaking

I can have a dicussion with a classmate
about cybercrime.

 

 

 

Step 2 - Reading

I understand the reading.

 

 

 

Step 3 - Grammar

I understand and can use the grammar 'reported speech'.

      

Step 4 - Task

I can do the writing task.

 

 

  

 

What have you learnt in this period?
Answer the following questions:

  • What was the easiest part of this lesson?
  • What was the most difficult part?
  • What did you already know?
  • What was new to you in this lesson?
  • What do you have to ask your teacher?

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    Auteur
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    Laatst gewijzigd
    2025-05-11 22:44:36
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    Toelichting
    Deze les valt onder de arrangeerbare leerlijn van de Stercollectie voor Engels voor vwo, leerjaar 4, 5 en 6. Dit is thema 'Crime'. Het onderwerp van deze les is: Forensic science. Deze les gaat over forensisch onderzoek. Daarbij worden verschillende types forensisch bewijs genoemd, zoals vingerafdrukken of DNA. Daarnaast wordt er een 'crime report' geschreven.
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    3 uur 0 minuten
    Trefwoorden
    arrangeerbaar, bewijs, crime report, dna, engels, forensic science, forensisch onderzoek, stercollectie, v456, vingerafdrukken

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    Forensic science h45

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    Lipstick can now be used to solve crimes

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