History
How Do We Know the Age of Earth?
Earth is about 4.54 billion years old, determined mainly through radiometric dating of meteorites and the oldest Earth and Moon materials.
History
Explore civilizations, inventions, evidence, and human change.
History
How Did the Industrial Revolution Change Society?
Mechanization, fossil energy, factories, and new transport increased production while transforming cities, labour, public health, inequality, and the environment.
History
How Did Ancient Civilizations Build Huge Structures?
Ancient builders combined skilled labour, surveying, ramps, levers, cranes, waterways, standardized parts, and organized supply systems.