STEM Toys for Toddlers ，Fingerprint Experiment

Are there are simple STEM toys for Toddlers?  Of Course.

Recall the detective movies and TV dramas you’ve seen, such as the well-known detective Conan, Sherlock Holmes and so on. Such a scene is often seen in TV plays. When a detective or a policeman searches the criminal’s murder weapon, he will collect a very important evidence left behind by the suspect.

Do you know what that is?

Yes, it’s fingerprints.

How are fingerprints collected?

The distribution of lines on each finger of each person is different, and the distribution shape of lines remains fixed throughout one’s life. Even twins have different fingerprints.

When we touch things around us, we actually leave our fingerprints where we touch them. Fingers and other parts of the skin have sweat glands, as long as you touch something, there will be a small amount of sweat residue. At this time, when we touch something with powder, sweat will absorb the powder, and the invisible fingerprint will come out.

Why is it called human ID card?

Because the repetition rate of fingerprint is very small, it is called human ID card.

What is the probability of fingerprint repetition?

About 1 in 15 billion.

When the fingerprints start to appears?

The fingerprints start to appear when they are only 3 or 4 months old.  And they will accompany us all our lives.

What is the use of fingerprints?

Because fingerprints have the characteristics of “different, unchanged for life”, they are widely used in the fields of entry inspection, search crime and so on.