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Notes for the Instructor

Hair is the thread-like material that grows from the skin of mammals – including humans – and a few other animals. Each species of animal has its own identifiable type of hair with consistent length, color, shape and roots. The hair also has internal features that can only be seen with a microscope.

Animals can have different types of hair on their body. In humans, hairs found on the head have different characteristics from hair found on other body parts. Animals have coarse outer hairs, fine fur hairs, whiskers, and often other hairs from the tail.

Hair is a common type of trace evidence found at crime scenes. This is because it can easily be transferred during physical contact (Locard’s Exchange Principle). The types of hair found and number of hairs found at a crime scene all impact their importance as evidence. Investigators first determine the species of animal from which the hair came. Then, specific comparisons of an individual’s hair and the crime scene sample under a microscopic help link the suspect to the scene.

In this lesson, students will be studying human head hair samples and making comparisons between these hair samples and some found at our crime scene. They will view the hair with the naked eye and then with hand lenses. Students will attempt to match the crime scene hair to that of a suspect.

Students will also learn to make their own slides from a transparency. Young scientists can use this skill at home with any lightweight plastic material, a piece of paper and some tape. In the last lesson, they successfully made a slide using only wide adhesive tape.

Now it’s time for the students to try to determine the source of the hair found at the crime scene!

The activities in this lesson address Next Generation Science Standards practices of Planning and Carrying Out Investigations and Analyzing and Interpreting Data. In addition, they address Common Core Learning Standards. See the appendix on page 105 for more details.