Erupting science experiments are the best! Why not make a Valentines Day science activity with two interesting demonstrations for kids. Explore liquid density and a fun chemical reaction too. We have tons of fun Valentine science experiments for you to try!


Valentines Day science activity for kids chemistry. Explore both liquid density and a cool chemical reaction with our homemade lava lamp


Young kids and science mix really well, unlike oil and water! Simple science activities you will find on our site also have a playful element to them. We love really fun, hands-on science activities that are easy to set up.

Science experiments can easily be changed up for seasons and themes. That’s a wonderful way to revisit science concepts without it getting boring.

This Valentine’s Day science activity asks some great questions! Do water and oil mix? Why or why not? Why does Alka Seltzer tablets cause the bubbles to form? Why does it erupt?

Make sure to ask these great questions before you start the different phases of your experimenting. You can teach kids how to make a prediction or a hypothesis with just a few simple questions. Add our printable science journal pages to extend the learning for older kids.

Valentines Day Science Activity

Give kids time to examine and observe the changes they can see happening. See full set up below!

Examining chemical reaction for Valentines Day science experiment

There’s a lot of room to explore and get creative with this simple science activity. Mix and add to your hearts content. You can easily set this up as a potion mixing table. We love potion mixing for year round science.

MAKE SURE TO CHECK OUT: Potion Mixing Science Table

Exploring a Valentines science fizzy eruption



  • Baby Oil {Cooking Oil Will Also Work}
  • Water
  • Bottle {We Like Voss Bottles}
  • Food Coloring
  • Alka Seltzer Tablets {Store Brand Works!}
  • Plastic Hearts Optional


STEP 1. Have your kids add either the water or oil first to the bottle. I recommend adding both liquids. Make sure to stop and observe what is happening!

STEP 2. Next add color. Of course we chose red for Valentine’s Day but you can really choose any color! Take a look at our other colorful lava lamp experiment.

You can also drop in plastic hearts just for an extra touch of Valentine’s Day fun. Make sure to note if they sink or float.

Valentines Day science activity supplies

STEP 3. Now’s the exciting part, break up your alka seltzer tablets into 1/4th’s or 1/2th’s. Add one piece at a time to the bottle and observe what happens!

YOU MAY ALSO LIKE: Alka Seltzer Rockets

Valentines Day science activity with Alka Seltzer eruption chemistry


Let’s start with exploring liquid density. What happens when you add the oil to the water or vice versa? The two liquids separate. Oil is lighter than water and oil does not dissolve in water, so it floats to the top.

Put the cap on the bottle and shake it up! What happens immediately? What happens over time? The liquids will always separate. You can also add rubbing alcohol or corn syrup and check out what happens.

CHECK IT OUT: Make your own density tower!

Now what about the Alka Seltzer tablets? Have you ever had a tablet in a glass of water for a yucky tummy? Do you remember the fizz? The tablet contains an acid/base mix that when combined with water produces a gas, carbon dioxide.

Carbon dioxide causes all the bubbling fizzing action. If you use a container that is narrow and you use extra pieces of tablet, you can make it erupt. The gas has nowhere to go but up and out.

Now if you don’t add a ton of tablet pieces at one time, you can observe the colored water bubbles that rise up through the oil and sink back down again. This gives you that lava lamp look.

Valentines Day science activity

The two liquids, water and oil naturally separate. Oil is lighter than water.

Valentines Day liquid density science activity

Adding an Alka Seltzer tablet will make your Valentines Day science activity look like a lava lamp.

Valentines Day science lava lamp idea

If you have a kid like mine, he’s way more interested in adding all the tablets at once.

Valentines Day science activity for kids

Because things that erupt are always the coolest!

CHECK IT OUT: Erupting Baking Soda Vinegar Volcano

Make science super fun for kids and you will be providing an awesome base for the future. The ability to make observations, conduct experiments, trouble shoot, and think critically are just some of the great qualities a simple science activity or STEM activity can encourage!

Erupting Valentines Day Science Activity and Lava Lamp



Make sure to check out these other awesome Valentine’s Day science ideas too.



  1. This is really cool! I teach a program called Cradle School and the kids and parents, LOVE anything that bubbles over! I can’t wait to do it with them. Thanks!

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