Forensic Science for Kids -- Sand Mystery

This is a great way to study forensic science for kids. If you don't want to do it as a murder mystery, then modify it so that the culprit, "borrowed" a teddy bear, and took it to the beach.

With this modification, I have successfully done this activity with 3rd graders.

I created this mystery after reading about two murders which were solved by using geology.

For this activity, you will need:

• Several sand samples
• Hand Lenses or Dissecting microscopes
• Magnets (Kept inside a ziplock bag)
• Acid (such as Vinegar) and Droppers
• Petri Dishes or Microscope Slides
• Sieve Set (These can easily be made at home by purchasing screening, and using any stackable round object, such as large yogurt containers, but click on the link to see the picture.)

Write a short murder mystery where someone (I always used myself) is murdered, and there are number of suspects. The body is discovered in buried at a black sand beach, and...

... as it’s being dug up, several of the students notice that there is a different color sand on the body.

They surmise that the murder must have originally happened at another location, and that the body was moved from that other location.

There are a number of suspects, who all have beach homes. If the students can figure out where the murder was committed, then they will have identified a suspect.

The students will analyze five characteristics of the sand.

• Size
• Angularity
• Color
• Magnetism
• Reaction to acid

Size

Use the sieve set. Stack the sieves so that the largest sieve size is on top. Pour the sand into the top sieve, and shake it so that the sand grains separate out based on their size.

Angularity and Color

The magnifiers (or dissecting microscope) can be used to observe the sand. Sand is very beautiful when magnified, so don’t hurry the students through this part. You may, in fact, ask them to draw the sand.

Use this picture to practice describing the color and angularity:

This sample is all white, so you would say:

“100% White."

But it has a mix of grain shapes. I would say:

“50% angular,” “50% slightly rounded."

You can end your study of forensic science for kids at this point, but you can expand it to include three more properties of sand.

Magnetism

Put your magnet inside a plastic bag, and run it through the sand. If there are iron particles present in the sand, the magnet will pick them up. To return the iron particles to the sand, hold the bag above the sand, and remove the magnet from the bag so that that iron particles return to the sand.

Reaction to Acid

The vinegar tests for the presence of shell fragments in the sand. (Coral and many seashells are made of Calcium carbonate. Vinegar reacts with carbonate ions to produce Carbon Dioxide bubbles.) The sand will fizz if it contains carbonate ions.

Test the samples while looking at the sand through a hand lens or microscope to detect smaller amounts of calcium carbonate.

Solving the crime

Now the students can examine the sample which was found on the body. By matching the sample, they can identify a suspect.

If they aren’t positive, they should re-examine the sand samples.

In conclusion, this is a great way to study forensic science for kids. With older kids, do it as a murder mystery, with younger learners, they can figure out who "borrowed" a teddy bear.

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