There seems to be two distinct issues here.  One, is it appropriate to use
students (of whatever age) during an archaeological study (CRM - Research -
Field School [which should be under research]), and two, should real sites by
used for educational purposes.
 
On the first, limitations on public participation - including students - are
to be made on a case by case basis by the PI with respect to whether the
integrety of the study can or can not be maintained.  If Dan Mouer does not
feel comfortable with elementary school age students on his sites, then this
is an appropriate decision.  End of discussion.
 
Bill Lipe's comments seem to be directed more towards the use of real
archaeological sites for educational purposes.  Here the age limits must be
based on the teacher's (and here I include the PI archaeologist either as the
teacher, or as part of a team leading the program) limits to reach certain
age groups.  The ability of the student (particularly based on age or grade
level) is not the issue.  The appropriate design of the educational program
with respect to both the participants and to the archaeological resource is
the issue.
 
In either case, the responsibility of the archaeologist toward the site
(resource) must be undertaken at the same level -- controled data recovery,
recording, and publication of results.  I do not advocate sacrificing the
resource for education, but neither sould we as professional scientist
advocate sacrificing the publics' concerns and interests to maintain an image
of professionalism.
 
Douglas