David Sousa's "Brain-Friendly Learning for Teachers" from the June 2009 issue of ASCD's "Educational Leadership" serves as a good source of information for improved professional development activities. Sousa's premise is that planning and implementing ongoing professional development with adult brain research in mind will make these experiences more likely to be successful. Adults, Sousa argues (anecdotally), are most powerfully motivated to learn when the experience seems likely to increase their ability to be effective in their work. This is a major take-home point for professional development in education, which, in my experience, is often done in large groups and is rarely differentiated. Although there are certainly aspects of our roles as teachers that are shared no matter what the subject area, it's important to keep in mind (particularly at the high school level) that educators are passionate about the subject(s) they teach, and that methods for effective teaching can vary significantly across subject areas. With those differences in mind, good professional development should incorporate small group "break-out sessions" in conjunction with large group presentations and discussions, so that the nuances of subject-specific teaching can be addressed and participants will be more likely to feel that the experience is going to make them more effective in their teaching.
Sousa's subsequent suggestions break down into four influences on adult learning; though these factors influence learning at all levels, Sousa suggests that adults are affected by them more powerfully given their advanced development relative to adolescents and children. The four factors are: emotions, feedback, past experiences, and meaning. While my own experiences of "sit and get" professional development have done a fairly good job of bringing in prior experiences and presenting topics in a meaningful way, a consistent critique I've had (and heard from many others) is that it's not realistic - or good teaching practice - to expect that we'll understand new information when it's presented only once, let alone without the time to really "digest" or get feedback on our attempts at implementation. When expectations are unrealistic and when the experience is so homogenized as to be of limited utility, negative emotions can build and interfere with the learning experience. However, an individualized professional development experience that will receive ongoing attention is likely to induce positive emotions in participants, thereby increasing the likelihood that good learning will take place that day and beyond.