This is what the planet Venus looks like from space. Venus is the second planet away from our Sun - Mercury is closer to the Sun, and then the Earth is a little farther from the Sun. [...]
Mars, the way the planet looks from space Which planet is Mars? The closest planet to Earth is Mars, and Mars is also the planet that seems most likely to have life on [...]
Molten lava: the beginnings of planet Earth What is the Earth made of? Most of the molecules that smashed together to make the Earth were iron. The smashing together released a [...]
Photons - Sunshine breaking through the clouds. When did the first photons appear? A photon is a tiny little particle of light, far too small to see individually. All light is [...]
Joseph Rainey, first black congressman in American government African-Americans in Congress After the Civil War, in 1865, the United States changed its Constitution to make slavery illegal. For a few years, black [...]
Native American food: Inuit carving of a sea lion Hunting and gathering wild food Early on, until about 2000 BC, people in North America ate only wild foods that they could hunt or gather. More about [...]
Corn, beans, and squash growing together When people in South America began to farm corn and beans and squash, they worked out a system for growing all three plants in the same field that was [...]
Sine wave In order to save energy, many, many things in nature move in a kind of repeated pattern we call a sine wave: water waves, sound waves, light waves, [...]
This is a hexagon. See, it has six sides that are all the same length. Definition of a hexagon A hexagon is a flat shape, all in one plane, with six [...]
A vase from Neolithic Sesklo, in Greece (5000 BC) Neolithic government As places got more crowded, in the Neolithic or New Stone Age period, some people began to live in [...]
