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The ocean
The ocean covers more than 70 percent of our planet and holds about 97 percent of all its water. Find out why sea water is salty, why an egg floats in salt water, what lives in the sunlit top and the pitch-dark deep, and calculate the crushing pressure at the bottom of the Mariana Trench. Three ages, each with a text, an experiment, a game, a quiz, a printable worksheet and a teacher sheet.
Ages 6–7The big blue oceanMost of our planet is covered by salty sea water. Find out where the salt comes from, what lives in the dark deep, and make an egg float!Ages 10–11Inside the ocean: salt, layers and pressureWhy is the sea salty, why does fresh water float on salt water, and what are the sunlight, twilight and midnight zones? Then run a fair test: how much salt does it take to float an egg?Ages 15–16The ocean in numbers: pressure, light and saltCalculate the pressure at the bottom of the Mariana Trench, test NOAA's figures, measure the density of model sea water and discuss what we really know about the oxygen made in the ocean.