Fingerprint Forensics

This weeks kids STEM activity was inspired by Penny the Police Officer and her detective work to find people and match them to a crime using fingerprint forensics, the study of our fingerprints.

The science of fingerprints is pretty interesting and a perfect start to a creative problem solving STEM activity. Kids are naturally curious and have their ‘detective’ questions well practised – how, why, how.

This kids STEM activity will start by exploring their own prints and then can be extended to a pretend crime scene activity using fingerprints from a variety of people.

What are fingerprints?

Each person has a unique set of fingerprints, even twins have a different set of prints to each other. Our fingerprints are made from tiny wrinkles in the skin and fall into three main patterns that you can see: arches, loops and whorls. When detectives collect prints there are two types, patent and latent.

Patent prints are made into soft surfaces like soap or wet paint and can easily be seen.

Latent prints are invisible prints that are left on surfaces. Oils in our skin leave a residue on everything we touch. By using a light powder to stick to this residue detectives can ‘lift’ the print and use it to study the patterns. Our kids STEM activity will be to collect these invisible prints and identify their main patterns

Collecting fingerprints

The easiest way to collect prints is by using an ink pad then pressing onto white paper. I’m not a huge fan of ink pads (particularly with active toddlers!) so try using a pencil, the graphite collects in the groove of the print and can be transferred onto clear tape.

draw onto a piece of scrap paper to make a coloured in section
push fingertip onto pencil
place a small piece of clear tape over the top of fingerprint, press down and collect the print
stick the print to a dark piece of paper/card or to our free printable

Use our free printable to compare prints and identify the main parts to each print.

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Use the Fingerprint Analysis Process called ACE-V

Analyse – assess the print and make sure it can be used for comparing. Look at the features and patterns: Is it a full print or partial? Can you see any patterns in it

Compare – view the known and suspect prints side-by-side to determine if they match

Evaluate – decide if the prints are from the same person or a different person. If there is not a match the results are called Inconclusive results

Verify – Ask a friend. Get someone else to analyse, compare and evaluate to see if they come up with the same conclusion

Extend the activity

Extend the activity by faking a crime scene – a toy has gone missing, something was moved to a different room or perhaps some cookies have gone missing from the jar. Gather fingerprints and compare them to prints of people living in the house – catch the ‘thief’