Drop an ice cube into a glass of water and something funny happens — it floats! It bobs at the top instead of sinking to the bottom.
That is strange, because ice is just frozen water. How can frozen water float on the very same water it came from? 🤔
By the end you'll be able to explain it to your family like a real scientist. Tap Next to start!
Things float when they are lighter for their size than the water around them. Scientists call this being less dense. Tap each object to find out if it floats or sinks.
Floaters are less dense than water. Remember that word — we'll use it for ice!
Water is built from billions of tiny pieces called molecules. In liquid water they slide around and snuggle up close together, filling every gap. Tap the water to see them wiggle!
When water gets very cold and freezes, the molecules stop sliding. They lock hands into a neat hexagon frame (a six-sided shape) — and that frame has big empty gaps inside it!
Drag the loose molecules onto the glowing dots to build the ice frame and see the gaps appear.
Because the ice frame has empty gaps, the same amount of water spreads out and takes up more room when it becomes ice. More room for the same stuff means ice is less dense — so it floats!
Which box has more empty gaps? Tap it.
Time to be the scientist. Drag the ice cube down into the tank and let it go. Watch what your less-dense ice does!
👆 Drag the ice cube into the water…
In cold countries, lakes freeze in winter. Because ice floats, it forms a roof of ice on top. Underneath, the water stays liquid and warmer — so fish and plants can keep living all winter!
If ice sank instead, lakes would freeze solid from the bottom up. Tap each card to see what floating ice protects.
What you learned:
💧 Things float when they are less dense (light for their size).
🧊 When water freezes, molecules build a hexagon frame with empty gaps.
📏 The gaps make ice take up more space, so ice is less dense than water.
🐟 Floating ice makes a roof that keeps fish and plants safe in winter.
Try saying it out loud: “Ice floats because freezing spreads the molecules apart, so it's less dense than water.” 🌟