Title: Fingerprinting (KS3)
Previous Knowledge:
 Pupils should know already that every individual has unique DNA (with
the exception of identical twins)
Resources:
Ink pads, chalk, police tape,
murder weapon, talc/ pencil
graffiti, pictures of fingerprint
types
Learning Objectives:
Pupils will be able to
 Explain why every individual has unique fingerprints (with the exception of identical twins)
 Explain why identical twins have the same DNA
 Identify and name the different types of fingerprint
 Correctly match up identical fingerprints
 Calculate probability
 Suggest alternative ways forensic scientists may correctly identify a criminal
Lesson
Activity and Focus
Content:
Pupils should enter to a police murder scene (chalk outline of body on the floor, police tape and
Starter 10
murder weapon, area dusted for fingerprints)
Ask pupils to observe the crime scene and note down evidence
15
Explain that this lesson they are crime scene investigators and they must use the fingerprints left
Main
on the murder weapon to determine which member of the class is the murderer (this needs to be
arranged secretly in advance, the pupil leaving their fingerprints on the weapon)
Explain to pupils that every individual has unique fingerprints and why. Ask pupils if identical
twins have identical fingerprints. Show pupils the various types of fingerprint. Ask pupils the
probability of it being the person to their right.
15
Pupils record their own fingerprints
5
Pupils swap with the person next to them. One at a time pupils compare these fingerprints with
those left at the crime scene
Once the murderer has been identified, explain that more detailed analysis of the fingerprints must
Plenary 10
be done to confirm their identification as the combination of fingerprint types are not enough to
go on alone (eg all whorls differ slightly from one another). If more than one pupil has that
combination pupils should make further probability calculations.
Finally, ask pupils to suggest other ways forensic scientists may correctly identify a criminal
Differentiation:
 Less able pupils should be given more teacher assistance and
opportunity should be given for peer support.
 Probability calculations should be carried out as a teacher-led exercise.
Keywords and Definitions:
Forensics, fingerprints, DNA,
whorl, loop, arch