Describes the Miller-Urey experiment and how it described the beginning of life on Earth.

Discover what lies beneath the sand in deserts. Contrary to popular belief, 80% of deserts are not covered in sand, but rather bare earth, revealing the bedrock and clay of a dried-out ecosystem. Learn about the unique erosion patterns...

Harvard University historian David Armitage discusses the question of how the past can be used to shape today’s policy, describing how policymakers should not only try to avoid making the same mistakes, but also consider worthy roads not...

In this video, Harvard intellectual historian David Armitage discusses his transition from exploring state formation in Britain in his first book to delving into the global impact of the American Declaration of Independence in his...

Learn about the formation of the Earth and its development over billions of year with this Space Explained video by KLT!

03 Vosotros commands - Practice 3

03 Vosotros commands - Practice 2

03 Vosotros commands - Practice 1

03 Ustedes commands - Practice 3

03 Ustedes commands - Practice 2

03 Ustedes commands - Practice 1

03 Usted commands - Practice 3

03 Practice Usted commands with a special guest! - Practice 2

03 Practice Usted commands with a special guest! - Practice 1

03 Nosotros commands - Practice 3

03 Nosotros commands - Practice 2

03 Nosotros commands - Practice 1

03 How to form Vosotros commands in Spanish

03 How to form Ustedes commands

03 How to form Usted Commands in Spanish

03 How to form Nosotros commands in Spanish

We've spent quite some time discussing igneous rocks, sedimentary rocks, and metamorphic rocks, their properties, and the conditions under which they form. Now it's time to zoom out and see how they are all connected in something called...

Princeton University physicist Paul Steinhardt discusses the spectrum of current scientific investigations associated with the quasicrystals he and his colleagues discovered.

It describes asexual reproduction and the modes of asexual reproduction in plants.