DIY Halloween Lava Lamps: A Fun Halloween STEM Activity for Kids

If you’re looking for a Halloween activity that is easy to set up, fun to watch, and actually teaches kids something, these DIY Halloween lava lamps are it!

They are colorful, bubbly, a little bit spooky, and they give kids the opportunity to explore some really cool STEM concepts using materials you probably already have at home.

It looks like play, but there is so much learning happening here.

Kids are predicting what will happen, observing changes, asking questions, experimenting with materials, and figuring out why things happen.

That is STEM play at its best.

What Is STEM Play?

STEM stands for science, technology, engineering, and mathematics.

For kids, STEM learning can look like:

• Mixing ingredients

• Building with blocks

• Testing what floats and sinks

• Making predictions

• Exploring cause and effect

• Figuring out how things work

• Solving problems

• Asking questions

• Testing an idea and trying again

  
  

When children have opportunities to explore and experiment through play, they are developing important skills that extend far beyond the activity itself.

The Benefits of STEM Play for Kids

1. STEM play encourages curiosity

Young children are naturally curious.

They want to know what will happen if…

STEM activities give them a safe way to explore that curiosity.

Instead of immediately giving your child the answer, let them wonder first.

• What do you think will happen?

• Will the ingredients mix together?

• What do you think will happen when we add the tablet?

  
  

Those simple questions can turn an ordinary activity into a learning experience.

2. STEM play teaches cause and effect

One of the biggest benefits of hands-on STEM activities is that children get to see cause and effect happening right in front of them.

They do something…

…and something happens as a result.

This is exactly what happens with our Halloween lava lamps.

Children can see what happens when the different materials are combined and observe the changes taking place.

That visual connection makes the science much more meaningful than simply telling a child how something works.

3. STEM activities build problem-solving skills

STEM play gives children opportunities to figure things out.

Maybe their structure falls down.

Maybe their experiment doesn't work the way they expected.

Maybe they need to change something and try again.

And that's okay!

We don't want children to think that there is always one right answer.

We want them to become comfortable with trying, testing, changing, and trying again.

Those are skills they'll use for years to come.

4. STEM play encourages observation

A good STEM activity gives children something to watch closely.

What changed?

What stayed the same?

What happened first?

What happened next?

These are early science skills!

Even something as simple as watching bubbles move through a bottle encourages children to slow down and really observe what is happening.

5. STEM play builds language

Don't overlook the language development happening during STEM activities.

As you play, introduce words like:

• Predict

• Observe

• Experiment

• Dissolve

• Bubble

• Float

• Sink

• Mix

• Separate

• Reaction

DIY Halloween Lava Lamp Science Experiment

Now let's make our Halloween lava lamps!

What You Need

• A clear plastic bottle or clear glass jar

• Vegetable oil

• Water

• Food coloring

• Alka-Seltzer

• sharpie (optional)

• Googly eyes (optional)

  
  

A note about materials: I recommend using a clear container so children can easily see what is happening inside.

For younger children, I also prefer a sturdy plastic bottle rather than glass.

How to Make Halloween Lava Lamps

Step 1: Fill the container with oil

Fill your bottle or jar about ¾ of the way with vegetable oil.

Step 2: Add water

Slowly add water to the container until there it is about an inch from the top of the cup.

You should see the water move through the oil and settle toward the bottom.

Step 3: Add food coloring

Add several drops of food coloring.

Watch what happens!

The food coloring will move through the oil and eventually mix with the water at the bottom.

This part is always fun for kids to watch.

Step 4: Add the fizzy tablet

Break an alka seltzer into a few pieces and drop one piece into the bottle.

And now…

watch the magic happen!

The tablet reacts with the water and creates bubbles of colored water that move up through the oil.

When the bubbles reach the top, they fall back down again.

It looks like a homemade lava lamp!

The Science Behind the Halloween Lava Lamp

Okay, here's the part I love.

It's not actually magic. It's science!

Oil and water have different densities and don't mix together.

The oil stays above the water because it is less dense.

Food coloring mixes with the water rather than the oil.

When the tablet is added, it reacts with the water and produces carbon dioxide gas.

The gas attaches to droplets of colored water and carries them upward through the oil.

When the bubbles reach the top, the gas escapes into the air and the colored water drops back down.

And then it happens all over again!

That means your child isn't just watching something pretty.

They are watching a chemical reaction, density, movement, and cause and effect happen right in front of them.

Why I Love Activities Like This

As a teacher, I have always loved activities that allow children to learn through doing.

Because when kids are interested in what is happening, they naturally want to investigate.

They want to touch it.

Watch it.

Ask questions.

Try something different.

And sometimes make a giant mess along the way.

That's learning!

STEM doesn't have to be complicated, expensive, or filled with worksheets.

It can be a Halloween lava lamp made with a few simple ingredients sitting on your kitchen counter.

Quick Safety Note

Always supervise children during sensory and science activities. Alka-seltzer tablets should not be ingested, and small Halloween decorations can be choking hazards. Use age-appropriate materials and containers, and have an adult handle materials that aren't appropriate for children to handle independently.

It is not recomended to put large quantities of oil down your drain. Use your descretion. You can put it in a bag or bottle with a lid and throw in the trash.