You don't have to watch a whistling teakettle to know when the water is hot. The kettle will \"tell" you when the water begins to boil. The kettle makes a long, loud whistle. When you whistle, you...
Speeding up molecules
Can you fry ice cubes? You can try---but if you heat ice cubes in a pan, they won't be ice cubes any more. The ice will melt into water. And, after a while, the water will boil and turn into steam....
Guessing Games
(two to twenty players) One player thinks of a person, a place, or a thing. The other players try to find out what it is by taking turns to ask up to twenty questions. A player can only ask a...
Pulling together
A rowing team is a group of people working together. If each man pulled his oar when he felt like it, the team would never get anywhere---much less win a race. So, like all teams, they have a...
The birth of the sea
The sea may have been formed by tremendous rains. Or, it may have been formed by steam from inside the earth. Scientists think the earth was formed more than four and one-half billion years ago....
Where the air came from
Scientists think the earth's atmosphere has changed during the billions of years since the earth was formed. At first, the atmosphere was probably very different from what it is now. It began to...
Hot-water fountains in the earth
On a bare, rocky patch of land sits a cone-shaped hump of rock with a hole in its top. Suddenly, with a hiss, a great, silvery spray of steam shoots up out of the hole. A geyser has erupted. Geysers...
Where did the ocean come from?
Scientists tell us that billions of years ago the earth was a ball of bare, sizzling-hot rock, with no air or water on it. The outside of the earth slowly cooled, but the inside stayed fiercely hot....