The floating egg experiment is one of the most visually dramatic science demonstrations for preschoolers: a fresh egg placed in plain water sinks immediately. The same egg placed in heavily salted water floats. Adding salt gradually, children can find the exact tipping point where the egg suspends in the middle — not floating, not sinking. This demonstrates the concept of density — that the salt water is "heavier" per cup than plain water — in a completely concrete, observable way.

The Experiment

1. Fill a tall glass with plain water. Gently lower an egg — it sinks. Record this.
2. In a second tall glass, dissolve 6 tablespoons of table salt in the same amount of water. Stir until completely dissolved.
3. Gently lower the same egg (or a second one) into the salt water. It floats! Record this.
4. Advanced: In a third glass, pour fresh water over the salt water slowly (along the side, not directly). Gently lower an egg — it will hover in the middle layer where fresh and salt water meet.

Science to Share

• Salt water is denser than fresh water — more mass in the same volume.
• The Dead Sea is so salty (10× saltier than ocean water) that people float on its surface without swimming.
• This is why ocean water supports floating better than lake water or pool water.

Frequently Asked Questions

What does "density" mean in simple terms for preschoolers?

"Density" can be explained as "how heavy something is for its size." Salt water is heavier for the same cup size than plain water — it has more "stuff" packed in. When the egg is heavier than the liquid around it, it sinks. When the liquid is heavier than the egg, the liquid "pushes the egg up" and the egg floats. You can demonstrate the same concept with layering liquids of different densities — corn syrup, water, and oil — to create a liquid rainbow in a glass.

Related activities: Toy Boat Races | Ice Cube Rescue Race | Sink or Float Experiment