I’m about to (again) begin working through Fux’s legendary introduction to counterpoint, Gradus ad Parnassus, which, as you may know, was required study for virtually every composer, from Bach, through Mozart and Beethoven, to Schoenberg, who (typically) revered it by denouncing it, in his own Preliminary Exercises in Counterpoint (for the 20th century and beyond).
This is primarily a philosophical, not musical exercise.
All that’s required is basic intelligence (ideally, but not critically, ‘mathematical’ intelligence), even more basic understanding of musical notation (not theory; maybe an hour’s work if you’re completely unfamiliar), discipline, and—if you’re lazy like me—the free composing app, MuseScore (https://musescore.org/en/download).
As counterpoint is one of the most fundamental and influential concepts in Western history, I don’t think its study should need much defense (it would be one of the key ‘values’ I’d teach to the children in my class—as per Dexter’s thread), but I should stress, for those who might be interested but worried, that the ‘steps’ are surprisingly undemanding and, I think, uniquely fascinating. It’s basically just a matter of applying a few simple, essentially mechanical rules to the harmonization of brief Gregorian-style melodies, and then (at least in my case) wondering at the beauty of it all and reflecting on the profound implications of such simple elements and relations.
The great benefit of 'stepping' as a group (besides the discussion) lies in having someone to correct one's inevitable errors (and, if lucky, ugliness)--in heuristic counterpoint!