It is recommended, see sample disclaimer below
TEACHER WEBSITES DISCLAIMER:
Warning. You are leaving the Andover Public Schools website. Andover Public Schools provides links to these sites for informational purposes only, and the presence of the link is not an endorsement of the site. Every reasonable effort is made to present current and accurate information; however, information changes over time, and external links may be removed. This is beyond our control. Please let us know if there are existing external links which you believe are inappropriate.