> Do you know of any successful boycott in which there was no way of
> witnessing who boycotted and who didn't -- and where the penalties as severe
> as they could be for isolated individuals boycotting the tests.
It is possible to do an organised boycott of testing - and I agree that that's the only kind that makes sense. In Australia last year the teachers' union threatened a boycott of the NAPLAN national literacy and numeracy standardised tests, and when the government suggested parents could supervise them, the parents' association refused to cooperate.
http://www.schoolsmatter.info/2010/04/australian-teachers-vote-unanimously-to.html
Ultimately the boycott was called off after negotiations with the union... But still, it shows the possibility.
Mike