How Do I Get Training?
You're a microscopist; you know your lab and your scientific field. You may even have graduate students. None of that means that you know how to really help a middle school teacher in a classroom. You need to know a bit about the changes that are happening in science education; the new methods are so successful that they're "trickling up" into collegiate education. You need to review the cognitive abilities of young folks. This won't take a lot of your time, but it's important.
The simplest way is to join a MSA local program, or attend a GEMS workshop; you'll find contact information on the preceding "How do I volunteer?" page. One of the "model" programs described on the RISE website www.nas.edu/rise may be located near you, and you can attend their training. If none of this is possible, get advice from RISE, starting with "Working effectively with students and teachers."
The North Carolina Museum of Life and Science produced "Sharing Science with Children" as two excellent pamphlets in the early 90s, and the advice is definitely not out-of-date. Both are available in downloadable form on the web: www.noao.edu/education/ncmlssg.html "Sharing Science with Children — A Survival Guide for Teachers" and "Sharing Science with Children — A Survival Guide for Scientists and Engineers".