Shake oil and water hard — which one ends up on top?
Golden oil and blue water just don't get along! Water holds onto itself so tight, like a crowd holding hands, that it squeezes the oil right out. So no matter how hard we shake the jar, they always come apart again into two layers. But here's the puzzle… when they settle, which one ends up on top — the oil, or the water? Make your guess, then we'll shake and watch!
After you watchShake oil and water hard — which one ends up on top?
The short answer
Oil and water won't stay mixed because water grabs onto itself very tightly and squeezes the oil out. Shaking only breaks the oil into tiny drops for a moment; the water pushes them back together and they float up into their own layer again.
The whole story
How it works
Water drops hold tight to each other, like a crowd all holding hands. Oil can't join that hand-holding, so the water squeezes it out into its own clump. When you shake the jar the oil breaks into tiny drops and it looks mixed, but the drops quickly bump together, join up, and float back to the top. Only a drop of soap, which can hold oil and water at the same time, keeps them mixed.
What people get wrong
Lots of kids think anything will mix if you just shake it hard enough. But shaking can't beat the way water grabs itself — the oil floats right back up within seconds. You need a helper like soap to keep them together.
Questions kids ask
Why doesn't shaking the jar harder keep oil and water mixed?
Shaking only breaks the oil into tiny drops for a moment. Water holds onto itself so tightly that it keeps squeezing the oil out, so the drops bump together, join up, and float back to the top no matter how hard you shake.
How does soap keep oil and water mixed?
Soap can hold oil and water at the same time. It wraps around each tiny oil drop so the drops can't touch and join back together, and the mixture stays blended.
Keep going
What else makes you wonder?
- If water holds itself so tight, what else might it refuse to let in?
- Soap can hold oil and water together — what else in your kitchen might do the same secret job?