🧪
Experiment
Salinity & Buoyancy Test
See how salt changes how things float — and what that means for fish.
20 min Easy
📋 What You'll Need
- •2 clear cups
- •Water
- •Salt (about 3 tablespoons)
- •2 small identical objects (a grape or small egg works)
- •A spoon for stirring
👣 Step by Step
🔍 What to Observe
- •Which cup made the grape float?
- •Did more salt change anything?
- •What does this tell you about why fish regulate salt in their bodies?
💡 Tips & Safety
- •The lagoon is brackish — saltier than fresh water, less salty than the ocean.
- •Fish have to manage how much salt is in their bodies depending on the water.
- •After heavy rain the lagoon gets fresher; after dry spells it gets saltier.