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Dancing Raisins (Zombie Eyeballs)

Ages 5+ with an adult10 minutesMess: Low
Grown-ups: please supervise this experiment the whole time. Read the safety notes first.

Drop raisins into fizzy water and watch these zombie eyeballs bob up and down all by themselves.

WOW FACT

Submarines rise and sink in a similar way: they change how much air and water they carry in special tanks.

🧰 What you'll need

A tall clear glassSo you can see the raisins move.
✔ You probably have this
Fizzy water or clear lemonadeFreshly opened works best.
✔ You probably have this
A glass of tap waterTo compare.
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RaisinsJust 5 or 6.
✔ You probably have this

✨ Want to go further? (optional)

Plastic science beakersSee-through beakers make the bubbles easy to watch.
View on Amazon (amazon.co.uk)
Kids' chemistry setMore safe experiments with bubbles and gases.
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Children's science experiment bookDozens of easy experiments for rainy days.
View on Amazon (amazon.co.uk)

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What to do

  1. Pour fresh fizzy water into the tall glass, and plain tap water into the other glass.
  2. Drop 2 or 3 raisins into the tap water. Do they sink or float?
  3. Now drop 2 or 3 raisins into the fizzy water.
  4. Watch closely: tiny bubbles start growing on the wrinkly 'zombie eyeballs'.
  5. Count how many times one raisin rises and falls in a minute.
  6. Check again after 20 minutes. Are they dancing faster or slower? Why might that be?

What's going on?

A raisin is a bit heavier than the same amount of water, so in tap water it sinks. Fizzy water is full of dissolved carbon dioxide gas that is trying to escape. Bubbles find it easiest to grow on rough, wrinkly surfaces, so they collect on the raisin. Enough bubbles act like tiny armbands and lift the raisin up (that's buoyancy). At the top the bubbles pop into the air, the raisin loses its lift and sinks again. As the drink goes flat there's less gas, so the dancing slows down.

Safety notes