Anyone who wants to explore the concepts of learning theory but not get bogged down with too much academia will find a wealth of information at adult.about.com/education. Most of it is easily accessible stuff to read, too!

Here, you'll find links to articles on a number of well-known theorists, including Carl Rogers (experiential learning), Howard Gardner (multiple intelligences), Malcolm Knowles (who developed 'andragogy' - a concept for adult learning).

A 1995 Stephen Brookfield article entitled Adult learning: an overview comes from the International Encyclopedia of Education, and examines four major research areas in adult education: self-directed learning, critical reflection, experiential learning and learning to learn.

30 things we know for sure about adult learning has sections on instructional design and in the classroom.

Adult Learning: Perspective Transformation versus Andragogy is a bit more 'heavy going', but like all the articles here, is easy enough to read and short enough not to get bogged down in too much discussion. It considers the need to recognise more than one theory when looking at adult learning.

About adult learning is actually a link to funderstanding.com, and has theories has a brief section on e.g. multiple intelligences, problem-based learning, behaviourism and control theory.

Principles of Adult Learning by Stephen Lieb is more concerned with putting theory into practice, but has some interesting but brief detail about motivating adult learners.

You'll find a couple of links on this site which are out of action, but all in all, there is plenty here to keep a reader occupied - TrainingZONE found it was drawn from one section of the site to another quite easily!