Forensic Science- Hair and Fibres Year 9 By Kaine Bodey

Learning intentions & Success criteria Students will be able to identify the structure of a hair and fibre sample Students will be able to distinguish the differences between each hair and fibre samples provided Students will be able to sketch their hair and fibre samples Success criteria Students are able to comprehend why hair and fibre samples are important in a forensic science investigation Students are able to complete a practical on hair & fibre samples and learn about the different make up of each sample. Able to justify the correct sample and explain why

Information page Part 1- Introduction page & Learning intentions and success criteria & Prior knowledge Part 2- What is hair and the main structures Part 2.1- Activity 1 (Hair) Part 3- What is fibres and the types Part 3.1- Activity 2 (Fibres)

Prior Knowledge On the sticky notes provided students will answer three questions regarding the topic. What is forensic science? (Orange sticky note) What is hair and fibres? (Pink) Why do we collect hair and fibres in a forensic investigation? (Green) Students will then be asked to stick their sticky note onto the white board.

What is Hair? Hair is a fine thread- like strand that grows from the skin of humans and some animals . Multiple strands of hair are grown on different parts of the body; Head, arms, legs, facial hair etc.) of humans and other species. Hair is made up of one particular protein called keratin, which gives each strand of hair the strength to survive. Hair shape is determined by the genes each individual has inherited by their parents. Hair can be damaged by heat, not maintaining , chemical products such as hair dye/colour and hair products.

Physical Evidence: The make up of hair Hair bulb- Is the starting point where hair will be produced from. The bulb is made up of living cells which grow and orchestrate the growth of the hair. Hair shaft- is the hair seen outside of each persons scalp Three main parts of the Hair shaft: Cuticle, Cortex and Medulla

Physical Evidence: The make up of hair Sebaceous gland- Is a small gland that produces sebum, which is secreted on the root of the hair, making the hair oily. Because the hair is coated by an oily substance, water will run off your head.

Three main parts of hair structure

1- Medulla Central core (Pencil example- Lead) The function of the Medulla is unknown, although the main idea of the Medulla is it supplies evidence to which hair it belongs to. (Every Medulla is seen to be different in humans and animals). Round cells make up the Medulla Thickness & Continuous structure or broken into parts. Some hair strands will have a Medulla. Although some may have partial or nothing present at all. Thick strands of hair will have a Medulla present, although hair strands that are fine may lack the Medulla.

2-Cortex Protein rich structure that makes up most of the hair’s total mass. The cortex determines the hair’s colour, shape, strength and even it’s flexibility. How thick, the colour, the surroundings are important or the cortex. Did you know- If a strand of hair is stretched out and returns to its original shape, the hair is seen to be healthy. If the hair reduces in size and shape the hair is unhealthy, which means the cortex is weak.

3-Cuticle Outer coating that acts as the protection barrier for the cortex and the medulla. The cuticle plays the part in letting in moisture in and out of the hair’s cortex. This contributes to the hair’s shine and the texture Contains pigment

Activity 1- Human hair The class will work together to figure out which two diagrams are the human hairs. This will require students to reflect on prior knowledge that they have learnt in this lesson so far. Teacher will ask volunteers to share their thoughts on the diagrams. Prompting this discussion hopefully students and teacher can come to an agreement on the final decision.

Class activity- Can you identify Human 1 & Human 2

Answer to Activity 1

What are Fibres? A fibre is seen to be a unit of textile material that is longer in length than in width. There are two types of fibres; Natural and Man- made fibres

Natural fibres Types of Natural fibres: Wool Silk Linin Cotton Fur Are fibres that come from plant and animal which can be spun into filament. Types of Natural fibres: Wool Silk Linin Cotton Fur

Man made/Synthetic fibres Synthetic fibres are made from chemicals. Polymerization will occur to prepare and combine components to make the fibers.

Natural vs man made Natural fibres are identified as a irregular shape that has many twists in the strand. Synthetic fibers are more smoothly described, they may also have long odd shaped outer lines.

Class activity 2 on Natural and Synthetic fibres Activity 2 – As a class the teacher will prompt the students to think about what they know about Natural and Synthetic fibres to work out the questions being asked. Students in the class will receive the opportunity to voice their opinion on what they might think the picture is.

Activity 2- Differences between Natural and Synthetic fibres

Answer for Activity 2 Natural fibres are more twisted and tangled. Synthetic fibres are smooth in sight.