For the past 10 years, I've been teaching science enrichment classes. One of my classes, LEGO Challenges, is built around the Dacta 1030 set. Without any directions, and using just the pieces in the set, students try to build the tallest tower, the strongest bridge, or the car that will go the farthest when rolled down a ramp. My students get started on a challenge, share ideas, and then refine and apply what they've learned from each other. If necessary, I'll demonstrate a helpful technique.
I don't let my students look at the instruction booklets until they have spent time building on their own. It's not that I'm opposed to instructions -- I just think they should follow some initial exploration.
I'll confess that I never warmed up to the first generation of Mindstorms. My own kids were too young for it, and where I work, other teachers led the robotics classes.
I'm looking forward to working with Mindstorms NXT, but my primary interest right now is the step before NXT. I want to give students the experience of working with studless beams and other Technic elements before they get to robotics and programming.
For instance, students need to get a hands-on feel for gear ratios by building their own gear box. Rather than following directions to build a basic chassis, students should first learn through trial and error as they try to build their own car. That way, they'll understand some of the reasons for overlapping and keeping the sides parallel.
LEGO Education just released a set that meets my "pre-NXT" objectives, the 9632 Science & Technology Set. Here's the blurb in the LEGO Education online newsletter.
I'll post a review as soon as I get my hands on it.