St. Patrick's Day Gold Coin Science Experiment for Kids

This St. Patrick’s Day gold coin science experiment for kids is the most incredible activity for your little leprechauns.Baking soda, vinegar, and gold coins, OH, MY!

Three photos show the St. Patrick's Day Gold Coin Science Experiment. The first photo shows green bubbles, the second shows a gold coin appearing from under the bubbles, and the third photo shows a hand holding four excavated coins.

This St. Patrick’s Day gold coin science experiment sizzles with baking soda and vinegar

I LOVE baking soda and vinegar experiments with my whole heart.

In fact, I love them so much that I buy both supplies in bulk from Costco, and I replace them more frequently than you might imagine.

30 pounds of baking soda and 10 gallons of vinegar? TOTALLY NORMAL. NOTHING TO SEE HERE.

Making science trays is one of my favorite ways to use this dynamic duo. Trust me, you’ll be hooked, too!

☘️ Related: Our GIANT 10-foot St. Patrick’s Day coloring banner will have your kids “Dublin” over with joy!

Two gold coins appear under baking sods after they're covered with blue, yellow, and green vinegar.

You’ll see why the St. Patrick’s Day gold coin science experiment is love at first sight

Kids love searching for, finding, and excavating toys.

According to my very precise calculations, our preschoolers have spent 6.2 billion hours over the years going on hunts for treasure, dinosaur bones, fossils, and more.

Imagine their delight when you invite them to find golden coins. Pure excitement!

☘️ Looking for more St. Patrick’s Day activities for kids? These will have your kids ready to sham-rock:

Materials

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Baking soda
Vinegar
Coloring – liquid watercolors or food dye
Eye droppers or spoons
Small bowls or jars
Gold coins
Shallow tray
Tweezers – optional

A shallow green tray has thirteen plastic coins spread around sitting in the bottom of the tray. Yellow and blue vinegar sit next to the tray.

How to do a St. Patrick’s Day gold coin science experiment

Quick overview: place, cover, squirt, excavate.

Place the coins in the base of a shallow tray. Spread them out so that there is space between them so that kids really have to look for the coins!

Cover the coins in a thin layer of baking soda. You only need enough to make it so you can’t see the coins anymore.

Squirt the baking soda with colored vinegar! As the two mix, you’ll see them start to sizzle and bubble, and you’ll begin to see the coins peek up and eventually float to the top.

Note: I made my vinegar blue and yellow so that they would make green when mixed – a leprechaun’s favorite color! I love adding in a splash of color theory whenever I can. It will still work perfectly if you don’t have coloring or simply want to keep the vinegar clear.

Excavate the coins from the tray using your fingers or kids’ tweezers.

That’s it! This tray will last much longer than it looks. Once all the coins have been excavated, you can rinse them off and start again.

A close up of blue and yellow vinegar squirt onto baking soda, bubbling and turning green.

Video

Some tips and tricks

Make your vinegar last longer by diluting it with water. Even a half-and-half ratio of water to vinegar still makes bubbles and sizzles. While the reaction won’t be as strong as vinegar full-strength, it still gets the job done.

No hands in the baking soda is really the only rule I have with baking soda and vinegar trays. This prevents kids from digging holes and grabbing the coins in just a few seconds. This is the best rule and truly extends the play! For this project, hands can only grab coins once they have floated to the top.

Dye your water with dried-out markers to make your own DIY watercolors. Dried-out markers that would typically be thrown away make excellent colored water.

A hand holds four plastic coins over the science tray.

Why are there gold coins for St. Patrick’s Day?

If you find the gold, he has to share some of it with you.

Alternatively, if you can catch a leprechaun, he will give you his gold!

Please let us know if you strike gold!

A close up of the St. Patrick's Day Gold Coin Science Experiment where a gold coin peeks out from the baking soda after being squirt with blue and yellow vinegar.

Your leprechauns will love this St. Patrick’s Day gold coin science experiment

It has everything kids love: mystery, science, teamwork, bubbles, and gold!

This is the perfect activity to celebrate such a fun holiday.

Frequently Asked Questions

What science concepts does this activity teach?

Kids will learn about chemical reactions, acids and bases, and cause-and-effect while engaging in hands-on sensory play.

Can this experiment be used in a classroom setting?

Absolutely! This is a low-mess, high-engagement science activity that works great for small groups or individual exploration.

How can we extend the learning after the experiment?

Encourage kids to record their observations, change variables (like using different types of coins or liquids), or read books about St. Patrick’s Day traditions to tie in cultural learning!