The two classical themes of adult education are andragogy and transformative learning theory. Andragogy involved the teaching of adults. Transformative Learning Theory was introduced by Mezirow (Taylor, 2008). However, the two became more relevant in adult education with the need for programs to teach adults new skills.
According to Taylor, 2008, Malcolm Knowles established the theme of andragogy in the 1800s. Andragogy looked at the way adults learned and the methods that could be used to assist adults in learning. Mezirow took the stance that learning needed to be measurable for it to be effective. He also identified an adult's ability to reflect on the learning process played a role in the adult adjusting what he or she had learned.
Eduard C. Lindeman looked at the social forces that caused changes in society and the need for education to shift with the changes. He viewed adult education as a part of life experiences that adults underwent that taught them things they needed to know. He referred to these situations as situational lessons. He believed that there was no place in adult education for pedagogy teaching methods.
Because andragogy looks at the way adults learn as being different from the way in which children learn, many of his ideas ran parallel to this concept. However, he also speculated that learning had to have some measurable outcome which ties in to Transformative Learning Theory (http://infed.org/mobi/eduard-c-lindeman-and-the-meaning-of-adult-education/).