Underwater Volcano (all ages)

Science experiments at home are a lot of fun! Who doesn’t love hot lava but that can be pretty messy. Here’s a fun mess-free experiment for all ages with a simple to set up!

You probably already have all the supplies at home!


  • 2 clear containers (glass preferred), make sure one container is large and one is small enough to put inside the larger one.
  • A rock to weigh down the small container
  • Water – hot & cold
  • Food coloring, we used red. You can mix red and orange or any color you’d like
  • Straw or Spoon for mixing


Follow these six easy steps for the best results!

  1. Fill the large container with cold water, set aside.
  2. Fill the small container with hot water, we used our kettle to boil it.
  3. Place the rock in the bottom of the small container.
  4. Add food coloring to the small container.
  5. Now, with an adults help: gently place the upright small container in the large container.
  6. Last step is to watch the eruption happen! Yay – you did it!

How to make it educational:

  • Explain to them why this happens: the hot water rises to the top because the molecules in it move super faster and therefore makes it expand and less dense causing it rise. My boys thought it was so cool!
  • Before placing the small container into the large one, ask – “what will happen if we put hot water inside cold water?”
  • Form a hypothesis (an educated guess) – “I think the hot water will spread into the cold water.”
  • Draw conclusions – “something in the hot water causes it to move out of the jar into the cold water. My findings support my hypothesis.”

The perks about this experiment:

  • No mess – unless you spill the jar of water (adults assistance maybe needed).
  • It keeps their attention – they will watch the water, enthralled in the movement of the colors. Point out the different colors forming together if you use multiple colors.
  • Simple supplies – most supplies you already have, if you don’t have food coloring, you can use Kool-aid.
  • Perfect for all ages
  • It’s so much fun and very cool!

This is a fun way to teach preschoolers and elementary kids the basics of science and the scientific method. YAY! They won’t even know they are learning!


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