What your Preschooler will Learn from this Preschool Science Experiment:

- That different substances can actually change the look of the metal—in this case coins

- If your preschooler is old enough, some basic chemistry

- How to perform an experiment

What You will Need for this Preschool Science Experiment:

- Eight small containers deep enough to hold liquid and a coin

- Four shiny pennies (the newer looking, the better)

- Four shiny silver coins (the newer looking, the better)

- Vinegar

- Acetone (nail polish remover) Note: For health reasons, you shouldn't let your preschooler handle or touch the nail polish remover

- Salt

- Hot water

- One egg

- Plastic wrap

- Paper

- Pen

What to do:

Step One: Create salt water using your salt and hot water. Stir to help the salt dissolve. Proportions really aren't important, though you should be able to dissolve most of the salt within a few seconds of stirring. Once the salt is dissolved and you can't see anymore salt within, have your preschooler taste it to show them the salt is dissolved.

Step Two: Break your egg and beat it so the yolk is broken and mixed into the whites.

Step Three: Pour a small amount of vinegar into two of your containers. You only need enough to submerge the coin. Do the same thing with your egg, salt water and vinegar, adding these substances to two of the containers.

Step Four: Label your containers.

Step Five: Add your coins. You're going to put one silver coin in each of the four containers holding different substances and a penny into the other four bowls. For example, you should have one penny in the vinegar bowl, and one silver coin in other vinegar bowl.

Step Six: Since this is a stinky experiment and your house can quickly become scented from the vinegar, egg and acetone, wrap your bowls in plastic wrap to keep the smell down or do this experiment outdoors in a shady spot.

Step Seven: Wait overnight or even a few days.

Step Eight: See what your coins look like. Over time your coins will tarnish and look like they've been at the bottom of the ocean for a while - creating pirate booty for your preschooler.

For the Adults: What's going on in this Preschool Science Experiment?

Did your silver coins tarnish in the egg? Probably not. Though silver will tarnish in the presence of sulfur (eggs among other things), our coins are not made of up pure silver. If you want, put something made of silver in a bowl with a whipped egg and see it tarnish.

With the pennies, copper reacts to the air around us--meaning over time pennies will tarnish. This is called oxidation and without getting too into chemistry, it means there are changes going on with the atoms. Copper will tarnish around salt and acidic substances (such as vinegar) with a similar chemical reaction to air; it just happens faster.

Variations:

- Take pictures of the coins before you dip them and then pictures afterwards so your preschooler can really see the difference.

- Note in a notebook what happened to the coins. Call the notebook your preschooler's scientific journal.

- Try this experiment with whatever you want to see if you can tarnish your coins.

Hi! I'm Theresa Halvorsen, the preschool science and nature writer for Preschoolrock.com. I have twin boys and am blown away by their fascination with preschool science and how the world works around them. I am always looking for fun and simple science activities so preschoolers can learn about science and the natural world. Please contact me with any suggestions, ideas or questions you have about this site.

Helpful Tips for Parents

• Use correct scientific vocabulary from the start: observe, predict, experiment, hypothesis, result, evidence. Children absorb vocabulary in context without explicit teaching.

• Science fear is learned, not innate. Preschoolers approach science with natural confidence — protect that confidence by keeping science joyful and low-stakes.

Frequently Asked Questions

At what age can preschoolers do science experiments?

Simple science exploration begins in infancy — dropping objects (gravity), banging surfaces (acoustics), mouthing materials (texture and taste). By age 2, children engage meaningfully with water play, sand science, and simple mixing experiments. Between ages 3–5, children can follow simple experimental protocols: predict, observe, record, and discuss results. The scientific method — hypothesis, experiment, conclusion — is accessible at age 4 with appropriate support. The best preschool science is the child's own curiosity, not a formal curriculum.

Related reading: See also our garden science guide and our weather science for more ideas on this topic.

🎓 Skills Your Child Will Develop

• 🔬 Scientific Method — Even a simple experiment teaches the predict-test-observe cycle that is the foundation of scientific thinking — and preschoolers who internalize this process approach problems with genuine scientific confidence.
• 🌍 Nature Literacy — Learning the names, habits, and relationships of plants, animals, and natural phenomena builds the nature literacy that connects children to the living world and lays the groundwork for environmental stewardship.
• 🔄 Flexible Thinking — When an experiment produces an unexpected result, children practice adapting their thinking — a form of cognitive flexibility that makes them more resilient learners across all subjects.
• 🤔 Critical Thinking — Making a prediction, testing it, and explaining the result develops logical reasoning — the ability to move from observation to explanation that underlies all scientific, mathematical, and analytical disciplines.

Have you and your preschooler ever wondered why some coins are shiny and others are dull or has your preschooler noticed how silver changes color over time? Recreate aged coins with this fun and easy preschool science experiment. You can even use this preschool science experiment to create 'pirate booty' that's been at the bottom of the ocean. Speaking of pirate booty, this preschool science experiment ties in great with a preschool pirate birthday party.

See what happened when my sons and I did this preschool science experiment on my preschool science and nature blog.