Instant Ice

(A Montessori Science Inspired Experiment)

This experiment can be an exciting way to dive deeper into the concept of phase changes that you learned in Different Properties at Different Temperatures. We just added new nomenclature cards on phase changes too! You can access them in our Online Classroom.

Time to Complete

  • 1-2 hours


Research & Hypothesis

  • What are some of the differences between liquid particles and solid particles?
  • What do you need in order to turn water from liquid to solid?
  • At what temperature does water freeze?
  • How long does it take for water to freeze?


Before you begin, put your “patient pants” on. This experiment can be very particular and may take a couple of tries. Trust us though, when you finally get it, the excitement is worth it!

Part 1: The Set-up

Ice, Water, and Salt
16 °F - 19 °F

Part 2: Instant Ice in a Bottle

Ice Crystals in a Bottle

Part 3: Instant Ice Tower

Ice Tower


  1. How long did it take to supercool your water bottle to the point where it could form ice?
  2. What does “supercool” mean?
  3. Go back to the questions from the beginning – would you change any of your answers?
  4. Which takes longer: water turning to ice, or ice turning to water?

How does ice form?

Imagine you’re building a card house. One by one, you stack each card in a perfect pattern to build a giant structure. It takes A LOT of time and energy.

Then, your friend comes over and knocks it down. That didn’t take very much energy.

The cards are like H2O (water) molecules. Making a cardhouse out of the cards is like freezing water molecules into ice. Knocking a cardhouse down is like melting ice. 

Water particles are liquid. They cling closely enough to touch each other, but they’re free to move around. Ice particles on the other hand are very rigid. They stay near each other in an organized pattern (like the cardhouse).

In order to go from ice to water, you only need a little bit of heat energy. You can break apart the organized structure of ice by raising the temperature above 32 °F (0 °C). If you put a piece of ice out on the counter, it will immediately start melting.

In order to go from water to ice, it takes more energy. It takes more energy to organize particles than it does to break them apart – just like how it took more energy for you to make your card house, and less energy for your friend to knock it down. 

If you lower the temperature of water below 32 °F (0 °C), the water will cool and cool until FINALLY it has enough energy to start organizing into ice crystals. Then, the rest of the water will turn to ice very quickly. Just before any ice crystals form, we say that the water is “supercool.” The water is colder than it’s freezing point, but it is still liquid.

You could do this in the freezer, but using the salty ice bath method helps it happen more quickly … can you think of why that might be?

Here’s a hint, it has to do with freezing point depression.

What is happening when the cold water bottle instantly turns to ice?

In part 2 of this experiment (Instant Ice in a Bottle), you try to catch the water right before the first molecules organize themselves. Then, you can give them some extra energy by hitting the bottle on the counter. That extra energy helps the molecules move around and get into a perfect position to start organizing into ice. 

How does the instant ice tower work?

In part 3 of this experiment (Instant Ice Tower), you use an ice cube as a seed crystal to start the freezing process. When the supercooled water hits the ice, the water molecules immediately align themselves with the organized, frozen water molecules in the ice cube.

You seem to have made “instant ice.” However, you just waited until right before ice formed on its own, and gave it a little extra “oomf.”

Why does the tap water freeze in the ice bath before the purified water?

The reason that the tap water freezes has to do with the minerals in it. The minerals in tap water give the water molecules something to cling to and start building ice crystals off of. Kind of like how you used an ice cube as a seed crystal in part 3 of this experiment. It doesn’t need as much time or energy as purified water to form ice crystals, because the minerals give tap water a head start.

Montessori Science Activities, Projects, and Questions to Extend Your Research

  1. Test other liquids to see if they have the ability to supercool as water does. 
    • What properties do you think a liquid needs to have in order to be able to supercool?
  2. Are there any practical applications to supercooling? In other words, what inventions use the concept of supercooling to help us answer a question or solve a problem?