John H. Falk & Susan Foutz 
Free-Choice Learning and the Environment [PDF ebook] 

Most environmental learning takes place outside of the formal education system, but our understanding of how this learning actually occurs is in its infancy. By surfing the internet, watching nature documentaries, and visiting parks, forests, marine sanctuaries, and zoos, people make active choices to learn about various aspects of their environment every day. Free-Choice Learning and the Environment explores the theoretical foundations of free-choice environmental education, the practical implications for applying theory to the education of learners of all ages, and the policy implications for creating new and sustainable environmental education opportunities.