Have you ever made a DIY lava lamp? We love to explore science with common items found around the house. A homemade lava lamp (or density experiment) is one of our favorite science experiments for kids. Combine two fun science concepts for a cool lava lamp experiment the kids will love to do over and over again! 


Homemade lava lamp


Get ready to add this simple lava lamp experiment to your science lesson plans this season. If you want to explore liquid density and chemical reactions, this is the science activity to try! While you’re at it, make sure to check out these other fun chemistry experiments.

Our science activities are designed with you, the parent or teacher, in mind!  Easy to set up, quick to do, most activities will take only 15 to 30 minutes to complete and are heaps of fun!  Plus, our supplies lists usually contain only free or cheap materials you can source from home!

We have heaps of fun variations of this alka seltzer lava lamp that are perfect for different themes and holidays during the year.


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.

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 share the same density.

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 liquid. Learn more about density here.

Now for the chemical reaction! When the two substances combine (alka seltzer 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 then falls back down.


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You can also do this lava lamp experiment with salt instead of alka seltzer tablets!


  • Water Bottles, Mason Jars, or Plastic Cups
  • Food Coloring
  • Baby Oil or Cooking Oil
  • Water
  • Alka Seltzer Tablets (generic is fine)

Lava Lamp Tip: Set up this experiment on a plastic tray or dollar store cookie sheet to minimize the mess. Dollar stores also have nice little mason jar-like jars you can use too. Science in a jar is quite fun, so we picked up six of them the last time we were there!

Check out our homemade science kit or engineering kit for more ideas about science supplies!


STEP 1: Gather your ingredients! We started with one cup, and then we decided to make a rainbow of lava lamps.

STEP 2:  Fill your cup or jar(s) about 2/3 of the way with oil. You can experiment with more and less and see which one gives the best results. Make sure to keep track of your results. This is a great way to turn a science activity into an experiment.

add oil to your cups or jars

STEP 3:  Next, you want to fill your jar(s) the rest of the way with water. These steps are great for helping your kids practice fine motor skills and learn about approximate measurements.

Make sure to observe what happens to the oil and water in your jars as you add each ingredient.

STEP 4:  Add drops of food coloring to your oil and water and watch what happens. However, you don’t want to mix the colors into the liquids. It’s ok if you do, but I love how the coming chemical reaction looks if you don’t mix them!

add food coloring

STEP 5:  Now it’s time for the grand finale of this lava lamp experiment! It’s time to drop in a tablet of Alka Seltzer or it’s generic equivalent. Make sure to watch closely as the magic starts to happen!

When the lava lamp chemical reaction slows down, add another tablet. What do you think will happen? How is the colored water moving up through the oil? Ask plenty of questions to get your kids thinking!

You can really get your lava lamp experiment going crazy by adding more tablet pieces but watch out… It might erupt out of the bottle! Be prepared for a little mess, but this homemade lava lamp is so much fun!

What else can you do with those aka seltzer tablets? What about making alka seltzer rockets!

add water to the oil


Want to turn this lava lamp into a cool lava lamp science project? Check out these helpful resources below.

What is a good question to explore for this lava lamp project? What if you didn’t add oil at all?  Or what if you change the temperature of the water?  What would happen? Learn more about variables in science.



Click on the photo below or on the link for more awesome ways to explore science and STEM with your kids!

science experiments and stem projects for kids


  1. Amazing. I’m a counselor for children and adolescents of all different functional levels and I love incorporating art into therapy. Thank you for this idea. It is so cool!

  2. Your welcome! So glad that this can be useful to you. My son loves anything that will erupt too!

  3. Baby oil works the best for this experiment. It is clear, so it allows for the food coloring to really stand out.

  4. Baby oil is great for this experiment but regular oil works well too in case you don’t have any on hand.

  5. How can I download instructions for the experiments? Iā€™d rather have a print out to check with during experiments than my phone.

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