In this case, I am not the teacher (not formally anyway). The composers were mere first graders at the time and tended to "quote" from what they know when asked to compose. So I suggested the use of 5/4 time to force them away from quoting (since they have not been exposed to any 5/4 music at the time).
Other tricks I have used in the past to nudge would-be young composers away from their comfort zones include suggesting the use of pentatonic scale (example here
, middle section is pentatonic) and Blues scale (example here
; coupled with the 12 Bars Blues progression) ... generally getting them away from the major/minor scales and the usual 2/4, 3/4, 4/4, 6/8 meters that young students usually get stuck with in their first few years of music studies, but still pretty tightly constraint so the would-be young composers still stay within a fairly small box (just a different box than what they're used to).
The formal teacher teaches the fundamentals, the classical, formal things; and those are all very important. That formal teaching is a full-time job all by itself (and it's a job that I would probably suck at if I try to do it). Since I operate outside of that formal/classical teaching system, I suppose I am in a good position to throw a few curve balls every now and then when I get involved.