Thanks for doing this research, Nikola.
The warning that the article is not saved is not clearly visible, and some
students have managed to not save their articles
without realizing that
they
have not saved them. The warning could be made more visible, but I believe
that
the best way of solving this would be to try to save the article by ajax,
and
to
display the captcha on the article editing page itself.
https://bugzilla.wikimedia.org/show_bug.cgi?id=19648 has been sitting for a
while. Patches welcome. :-)