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20+ Halloween Science Experiments You Can Do in a Jar!

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If you love Halloween science, and you love Mason jar science experiments, stick around. You’ll love these Halloween science experiments in a jar.

Halloween is a time for spooky stories, fun costumes, and Halloween STEM!

At our house it is! And these experiments are all Halloween science experiments in a jar.

Why? Because we love jar science experiments!

Why Halloween Science in a Jar?

We started doing science experiments in jars by accident. My kids kept breaking our “official” science flasks, so I started using glass jars instead. The glass jars were easy to use, and cost much less and were sturdier than the “real” science gear.

From there, I was asked to write the book “The Mason Jar Scientist,” and we’ve sort of stuck to jars ever since.

Why Halloween Science Experiments?

halloween science experiment collage that says "halloween science in a jar"

Hands-on science experiments are not only fun for kids in elementary and middle school, but they also help children see that science and STEM subjects don’t have to be scary or intimidating.

Science is really just a structured way to explore and learn about the world. Kids can think of science as a tool for creative discovery about life and the world.

The Halloween science experiment twist just gives a fun lens to learning about science and can be used as a tool to make science less scary for kids who may not be as into science.

halloween stem challenge cards

What Will Kids Learn Doing Halloween Science Projects?

halloween science experiment collage that says "halloween science creepy jar experiments"

In these specific jar science experiments, kids will learn about:

  • Chemical reactions
  • Chemical bonds
  • States of matter
  • Chromatography
  • Density
  • Blood
  • Crystals
  • Ionic and covalent bonds

The Complete List of Halloween Science Experiments in a Jar

halloween density jar with orange and yellow layers that says "15 halloween science experiments in jars"

These Mason jar science experiments are perfect for Halloween. Not all of these were originally done in a jar (it’s only been since 2017 that we’ve really targeted jars here at STEAMsational), but they would all work really well in jars.

A lot of these Halloween science experiments in jars are slime-related, because my kids were obsessed with slime there for a while, so we tried all sorts of slime variations!

Slime is easy to make in a jar, and we always make our slime bases in jars these days!

halloween science experiment collage that says "creepy jar experiments"

Without further ado, the Halloween science experiments in a jar!

Learn about chromatography and what colors are in a black marker with this Ghost Chromatography experiment.

Can you make blood boil for real? You can in this Boiling Blood Slime in a Jar experiment!

Density is more fun when it is creepy, like this Halloween Density Jar.

Is that a ghost? Is it slime? Is it science? It’s all three when you make Ghost Slime in a Jar.

Do monsters lay eggs? How does pickling work? Does dye penetrate through an egg shell? Learn all of that and more in the Halloween Monster Eggs in a Jar experiment.

Learn how crystals form, what type of bond salt crystals make, and what an ionic bond is in the Halloween Salt Crystallization Experiment.

We love making slime in a jar. The Eyeball Slime in a Jar experiment is particularly gross.

Make a slime that really bubbles just like a witch’s brew in the Bubbling slime experiment.

This spider leg potion isn’t made in a jar, but it could be. Make a Halloween Lava Lamp this Halloween!

You don’t have to have fancy science flasks to make this Mad Scientist potion. You can just use jars.

Make this Zombie Slime in a Jar and get creepy this Halloween.

Check out this osmosis experiment for kids and learn all about how osmosis works using an egg!

Kids will love learning about chemical bonds in the Skull Slime Science Experiment.

Check out the Jello Worms Experiment and learn about science and make something creepy at the same time!

You can also learn how to make a jello brain without a mold.

Try out this Spider web Slime Recipe and learn all about the science of slime!

halloween stem challenge cards

More Halloween Activities

Adorable Halloween Classroom Door Ideas with a Science Twist

11 Halloween Slime Recipes Perfect for Spooky Season

11 Halloween Fine Motor Activities that Will Delight Not Fright!

Halloween Handprint crafts

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