Drupal Schools Network

The quickest way: append /user to the URL  - if it's a Drupal site you'll be able to log in.

If there is a subdomain (e.g. site.com/main)  and the above test does not work, append /user after /main (e.g site.com/main/user).

If none of these work (the site might want to protect against spam) - try "contact" in place of "user" since most Drupal sites enable the /contact form.