Wanda,
I think you are spot on. The (inaccurate) adage in medicine of "see one, do one, teach one" does have a degree of truth that is realized in the field trip experience. I have seen many students become motivated and begin to buckle down following an interesting or pertinent field trip. I think as instructional strategies go, that's powerful! Engagement and drive to learn is internally driven. Inspired speakers or exciting field trips can very effectively create that inner drive.
Barry Westling