Khan Academy on a Stick

History of life on Earth

Earth is over 4.5 billion years old. How do we know this? When did life first emerge? From the dawn of Earth as a planet to the first primitive life forms to our "modern" species, this tutorial is an epic journey of the history of life on Earth.

Humanity on Earth

Where do we think humans come from? How and why have we developed as a species. This tutorial attempts to give an overview of these truly fundamental questions. From human evolution (which is covered in more depth in the biology playlist) to the development of agriculture, this tutorial will give you an appreciation of where we've been (and maybe where we're going).

Measuring age on Earth

Geologists and archaeologists will tell you how old things are or when they happened, but how do they know? This tutorial answers this question by covering some of the primary techniques of "dating" (not in the romantic sense).

Life in the Universe

Are dolphins the only intelligent life in the universe? We don't know for sure, but this tutorial gives a framework for thinking about the problem.