It has been 41 years since the late Wisconsin Sen. Gaylord Nelson launched the first nationwide grassroots demonstration on behalf of the environment known as Earth Day. The event was actually a national "teach-in" about environmental causes, and it is widely considered the spark that ignited the modern environmental education movement. Within months, President Nixon passed the National Environmental Education Act, and a new subject was introduced into the curricula of K-12 schools across the country.

http://thejournal.com/articles/2011/04/06/teaching-green.aspx