Learn how the different geological components that make up sand are formed. [2:28]

National Public Radio talks with Dr. Walter Willett, Harvard MD and nutritionist, about changes that need to be made in the 1992 US Food Guide Pyramid. Interesting as an introduction to this topic, with links to related stories.

The food system being broken is a phrase often repeated. But is it true? Different experts offer their insights about systemic practices and healthy food access. Spanish captions and transcript also available. [3:18]