CSI



Learning Intentions:

1. To become familiar with //chromatography// and be able to apply it to 'real life' situations.

2. To perform 'fair tests' in Science identifying substances and fibres.

3. Identify and group fingerprintsinto 3 main categories: Arch, Loop and Whorl.

4. Set up and carry out Scientific Experiments following the correct process of; Aim, Equipment, Hypothesis, Method, Results and Conclusion.

5. Work collaboratively with peers to solve problems using the skills learnt.

Lesson One - Paper Chromatography

Chromatography is a technique used for seperating mixtures. In all of the variations of Chromatography, a substance is placed onto or into a medium and then a solvent passes through the test substance, some of the test substance may be attracted to the solven and follow it up in the medium. Different types of molecules are transported different distances, causing them to seperate. In these activities, filter paper is the medium, solvent is the solvent and black ink is the test substance. Chromatography is used in crime labs to seperate the components of 'clue' substances such as blood, ink or other mixtures found at the scene of a crime. Chromatograms of these clue substances are then compared with those of the suspected sources.

__Chromatography Monday 9th May 2011__

__L.I__ I am learning the process of the chromatography and use this to assist with solving the crime.

__Aim:__ To use chromatography to distinguish which pen was used in the ransom note.

__Hypothesis:__ I think that ......................because.............

Black marker x5 Casade marker x14 Sharpie x3 Vivid x4

__Equipment -__ Beaker, felt pens, ransom note, filter paper, water, hand lens, masking tape and straws.

Method:

1. Gather samples of pens. 2. Draw a line across a strip of filter paper, 1-4cm from the bottom. 3. Attach to straw with masking tape. 4. Put filter paper in beaker, making sure the ink is at least 1-2cm above the water. 5. Observe. 6. Remove filter when water has travelled about 3/4 of the way up the strip. 7. Compare results with the ransom note results.

Results - 1. Black Ballpoint Pen 2. Vivid 3. Cascade marker 4. Sharpie 5. Black marker

Reflection - (write here what you have learnt during this lesson).

__Lesson Three - Kitchen Chaos Wednesday 11 May 2011:__

The kitchen cupboard has got very damp and the labels have fallen off some of the containers. From the label scraps it is found that there is:

Icing sugar baking soda salt cream of tartar cornflour

TASK - Make order out of chaos

Use a series of simple tests and good observations to find out what substance is in each container.

Caution: You are not allowed to taste them! Please use small quantities.

Aim: to find out what the substance is by carrying out a series of simple tests.

Hypothesis: I think that the substance in the different containers is;

Substance A - ............................. Substance B - .............................  Substance C - .............................  Substance D - .............................  Substance E - .............................

Equipment - Five containers with the different substances labelled A, B, C, D, E. - Eyedroppers - Vinegar - Magnifying Glass - Litmus Paper (red and blue) - Iodine

CLUES TO HELP YOU.......................

1. Cream of tartar is an acid, and turns blue litmus paper red. 2. Cornflour and sugar are neutral and don't affect litmus paper. 3. Salt and bicarbonate of soda are alkaline, that is they turn red litmus paper blue 4. Bicarbonate of soda fizzes when mixed with vinegar. 5. Iodine changes from yellow-brown to blue-black with cornflour. There are many different ways of telling the differences between substances. You could: * Smell them carefully. * Compare the way they dissolve in water. * Examine with a magnifying glass. * Test the acidity with litmus paper. * Test the reaction with vinegar and iodine.

Results: Substance A is .......................... Substance B is ........................ Substance C is .......................... Substance D is ..........................  Substance E is ..........................

__Lesson 3 - Fossicking for Fuels Friday 13 April 2011:__

__Aim:__ to determine properties of different fibres/materials.

(Record your results on the sheet provided then glue this into your Science book.)

__Equipment:__ 1. 3 different types of material. 2. 2 beakers 3. 3 test tubes 4. Force meter (spring balance) 5. Ruler 6. Felt pen 7. Magnifying glass 8. Tongs 9. Candle

THE TESTS

TASK ONE - HOW MANY FIBRES ARE THERE IN THE MATERIAL?

TASK TWO - WHICH MATERIAL IS THE STRONGEST?

TASK THREE - WHICH FIBRES SOAK UP THE MOST WATER?

TASK FOUR - HOW DO THE MATERIALS BURN?

TASK FIVE - WHICH MATERIALS STRETCH THE MOST?

(Record results on the sheet provided)

Lesson Four - Finger Prints __Wednesday 18 May 2011__:

Every person's fingerprint are as different as each person. The use of fingerprints is very important for the police whose only evidence at a robbery might be the fingerprints left by the thief. Police keep a record of fingerprints of criminals in banks of computers.

Different types of Prints

 Loop Whorl Arch

__Your Fingerprints__

Equipment - Pencil, Paper, Sticky tape, Magnifying glass.

Method 1. Rub the side of a pencil lead back and forth on a sheet of paper to build up the black area large enough to take 10 prints. 2. Press one of your fingertips firmly onto the black. Place the sticky side of a piece of tape over your fingertip. (You may need a friend to help you with this.) 3. Tape the print to the correct location on the fingerprint form. 4. Using the magnifying glass compare your prints to the pictures above and try to label them as either arches, loops or whorls.

__Lesson 5 - Hair Analysis Friday 20 May 2011:__

Learning Intention: We are learning to

1. think about the process involved in developing a technique for forensic analysis

2. identify the physical structures of hair

3. use our observational skills, critical thinking and microscopy

Background information Unfortunately hair is not the best type of physical evidence for establishing identity. It is not possible to show with any certainty that two hairs came from the same person or animal. However hair can be used to rule out certain suspects or scenarios. It can also be used to corroborate (support) other physical evidence if it is consistent with the rest of the evidence.

Guide to Identification

Cuticle - Outer coating composed of overlapping scales Medulla - Central core, this may be absent Cortex - Protein rich structure surrounding the medulla; contains pigment

Fill in the Identification Chart