Your comment on age group spread reminded me of this excellent series of half-hours (?) on PBS in early '80s - made in UK. The object was to demonstrate what *thinking* er *means*. This group was also ~ 8-80 yos.
A sample problem I recall was about "parking" problems - maybe best use of space in some area; layout, rules? etc. The suggestions were on many scales, with De Bono merely 'moderating' and occasionally directing towards a pregnant idea. I think.. this is available from PBS Videos.
Agree about the Lord/Flies nature of most schooling in the Westernish world. Accentuated natch - as class-size has grown to the Impossible/teacher. In my own case, that was ameliorated via the 'military discipline' overtones, which in hindsight I'd liken to home-school enviro, much more than to public schools du jour (or du This-jour).
These teachers (et al) weren't really manufacturing toy soldiers so much as -- spreading Parental authority. There were enough folks around us that, we couldn't gang-up and do stupid shit (well, after hours there was a certain amount of the usual savage sort - inevitably, but rarely.)
I never thought that *I* would be touting the virtues of (certain types of..) "Military Schools" !! (And there are types I would disparage as much today as always: those whose actual aim IS the creation of young cannon-fodder who obey orders forever next. And these invariably have a recognizable political agenda to mold.)
But.. IMhO: this one I happened to land in, not as a 'truant' but as a consequence of single-parent realities then - now appears to have been "a better environment in which to grow" than, most any public schools I have heard about and heard Too-Much about, of recent times.
FWIW
Ashton