Do you want to try a little spooky science this year? Our Halloween lava lamp experiment is perfect for your young mad scientists! Halloween is a fun time of year to try out science experiments with a spooky twist. We love science and we love Halloween, so we have tons of fun Halloween science activities to share with you. Here’s our twist on a classic oil and water science experiment.



Exploring liquid density is the perfect kitchen science experiment because you typically can find everything you need in the pantry, under the sink, or even in a  bathroom closet. Often you can use liquids you have on hand. We have done several density experiments in the past including homemade lava lamp and a rainbow water density tower.

 I thought Halloween would make a terrific opportunity to test out a classic science experiment with a spooky twist. This lava lamp experiment is a hit all year round but we can make it a bit creepy for Halloween by changing up the colors and adding accessories. Explore liquid density and add in a cool chemical reaction too!

You can check out even more of our awesome Halloween science experiments towards the end, but I will share now that we have had a lot of fun exploring brains and hearts this fall for some creepy science.


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  • Jar or beaker
  • Cooking oil
  • Water
  • Food coloring
  • Alka seltzer tablets or generic equivalent
  • Spooky Halloween accessories (We used some spooky spiders from the dollar store!)


Lava Lamp Tip: Set up this experiment on a plastic tray or dollar store cookie sheet to minimize the mess.

STEP 1: Fill a jar 3/4 of the way with oil.

STEP 2: Now go ahead and fill up the rest of the jar with water.

Make sure to observe what happens to the oil and water in your jar as you add them.

These steps above are great for helping your kids practice their fine motor skills and learn about approximate measurements. We eyeballed our liquids, but you can actually measure out your liquids.

STEP 3: Observe what happens when you add drops of food coloring to the oil and water mixture. We went with dark food coloring for our Halloween theme.

Halloween Science Experiment Lava Lamp

STEP 4: Now add an Alka Seltzer tablet and check out what happens. You can repeat as desired with another tablet.

Watch out this can also get messy especially if the kids sneak in extra tablets.

Did you know that oil and water don’t mix because they don’t have the same density? Read on to find out more.


There are quite a few things going on here with both physics and chemistry! First, remember liquid is one of three states of matter. It flows, it pours, and it takes the shape of the container you put it in.

However, liquids have different viscosity or thicknesses. Does the oil pour differently than the water? What do you notice about the food coloring drops you added to the oil/water? Think about the viscosity of other liquids you use.

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Why don’t all liquids simply mix together? Did you notice the oil and water separated? That’s because water is heavier than oil. Making a density tower is another great way to observe how not all liquids weigh the same.

Check out what happens with a combination of liquids when you try our spooky liquid density tower!

Liquids are made up of different numbers of atoms and molecules. In some liquids, these atoms and molecules are packed together more tightly resulting in a denser or heavier liquid.

Now for the chemical reaction! When the two substances combine (tablet and water) they create a gas called carbon dioxide which is all the bubbling you see. These bubbles carry the colored water to the top of the oil where they pop and the water drops fall back down.


Click on the photo below or on the link for more awesome Halloween science experiments.