Musk is the CEO and CTO of SpaceX, CEO and product architect of Tesla Motors and chairman of SolarCity. He is also the founder of SpaceX and a co-founder of PayPal.

Musk has revealed in the past that his own experience in public school was horrible, riddled with both bullying and lessons that were neither valuable nor interesting. Instead of forcing his children to endure a similar experience Musk has built them a school without grades and that takes a radically different "unschooling" type approach to learning.

"I didn't see the regular schools doing the things I thought should be done," Musk said.

According to Wikipedia:

Unschooling is an educational method and philosophy that advocates learner-chosen activities as a primary means for learning. Unschooling students learn through their natural life experiences including play, household responsibilities, personal interests and curiosity, internships and work experience, travel, books, elective classes, family, mentors, and social interaction. Unschooling encourages exploration of activities initiated by the children themselves, believing that the most personal learning is, the more meaningful, well-understood and, therefore, useful it is to the child. While courses may occasionally be taken, unschooling questions the usefulness of standard curricula, conventional grading methods, and other features of traditional schooling in the education of each unique child.

The term "unschooling" was coined in the 1970s and used by educator John Holt, widely regarded as the "father" of unschooling. While often considered a subset of homeschooling, unschoolers may be as philosophically separate from other homeschoolers as they are from advocates of conventional schooling. While homeschooling has been subject to widespread public debate, little media attention has been given to unschooling in particular. Critics of unschooling see it as an extreme educational philosophy, with concerns that unschooled children will lack the social skills, structure, and motivation of their schooled peers, while proponents of unschooling say exactly the opposite is true: self-directed education in a natural environment better equips a child to handle the "real world."

In the interview, Musk's description of his school seemed to match up perfect with this philosophy.