demonstrations:hair_sample_analysis

Hair Sample Analysis

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Cells and Microscopes, Forensics

Alternative titles: Forensic Hair Comparison

Summary

Students act as forensic scientists by examining hair samples collected from suspects and a crime scene. Using magnifying tools, they compare features such as color, thickness, and curliness to identify the most likely suspect.

Procedure

  1. Prepare a hair sample sheet with taped hairs from each suspect, along with one hair from the crime scene (the culprit’s).
  2. Optionally, mount hairs on labeled microscope slides for easier viewing.
  3. Set up microscopes or magnifying glasses at the station for closer inspection.
  4. Provide each student with a case book and pencil for recording observations.
  5. Have students examine each hair, noting color, length, texture, curliness, thickness, and other visible characteristics.
  6. Direct students to compare the crime scene hair to each suspect’s sample, identifying the closest match.
  7. Encourage students to explain their reasoning, highlighting which features led them to their conclusion.

Forensic Hair Comparison Lab - Heidi Hisrich:


Forensic Science and Hair Analysis - Marysusan Noll:


📄 Hair Sample Analysis - Science World: https://www.scienceworld.ca/resource/hair-sample-analysis-crime-fighters-station-4/

Variations

  • Provide fibers from suspects’ clothing along with one found at the crime scene and analyze them in the same way as hair samples.
  • Use digital microscopes to capture and compare images of the hairs.
  • Introduce hair samples treated with dye or heat damage to show how treatments alter microscopic appearance.

Safety Precautions

  • Handle microscopes and magnifying glasses carefully to prevent damage.
  • If cutting hairs for slides, use scissors safely and store them properly after use.
  • Keep all samples sealed or taped securely to prevent contamination or loss.
  • Wash hands after handling hair or fiber samples.

Questions to Consider

  • What characteristics of hair are most useful for comparison? (Color, thickness, curliness, and texture provide stronger clues than length alone.)
  • Why might length not be a reliable identifying characteristic? (Length can vary within an individual depending on when the hair was cut or shed.)
  • How could dyed or treated hair affect the analysis? (It may mask natural color or damage the hair, making comparisons more difficult.)
  • How can investigators be sure the hair came from the culprit and not a victim or bystander? (They must consider context, timing, and other supporting evidence.)
  • What challenges exist when collecting hairs from a crime scene? (Hairs may have been shed long before the crime or transferred from another location.)