What are the origins of PBS programming? More importantly, why did Sesame Street change Oscar the Grouch's Season 1 color from orange to green? 

Historically, the impulse to advocate for a non-commercial component of the American ether emerged as an outgrowth of progressive-era concepts of public space. Clear precedents, such as allocations for national parks, public schools, settlement houses, and land-grant universities had shown that a concept of national identity successfully germinated through pro-public policies and strategies.

When the broadcasting model of radio emerged in 1921, distance-learning administrators seized upon the new public cognitive space of radio that so easily transgressed vast geographies with immediacy to reach targeted agrarian, gendered, and immigrant groups. Through classroom lecture as well as 'uplift' and 'citizenship' programs, educators paternalistically attempted to assimilate populations through free education.

However, early educational radio was plagued by low funding and interest, poor aesthetics, and a lack of standard practices--problems that continued through WWII. In the 1950s, through educational technology research, network precedent, grants, and an efficient but decentralized infrastructure of program exchange, university and state-based stations began to produce television programming that was both effective and stimulating.

By the mid-1960s educators had learned to consolidate critical curricular content and experiential learning into the formal commercial conventions of children's programming and Classic Network Television. The result was a series of seminal programs that appeared on the Eastern Educational Network (EEN) such as The French Chef and Mr. Rogers' Neighborhood. But it was the Children's Television Workshop that most successfully incorporated production aesthetics such as editing, blocking, sets, and camera movement to advance television instruction for early childhood education.

As an example, in season one of the CTW's Sesame Street, Oscar the Grouch appeared as orange when singing "I Love Trash". In what was for the 1960s a fairly progressive production, race and class roles are reversed as an African-American adult educates a white child to the plight of a homeless man named Oscar in a diverse urban setting. For season two they decided to change Oscar's 'skin' to green, as green was an easier color to film. This seemingly minor aesthetic decision exemplified a striking evolution from the poorly executed educational radio lectures of the 1920s to the trial-and-error production methods of PBS. Hence a core integrant of the history of public broadcasting includes the development of educational technology from classroom extension services to formal approaches to 'educational entertainment' on national public media.