The University of Phoenix offers an online school nurse graduate certificate. This online learning program consists of 24 semester hours. The entire program can be completed online. You'll take classes such as school nursing practice, health and disease management, and health assessment of the school-age child. This program was designed so that state and national school nurse standards could be met through this program.
The University of Illinois offers a school nursing certificate program which is mostly online. You have to meet on the Chicago campus once at the beginning of the semester, and again at the end. The rest of the classwork is completed online. Out of state students do not have to meet on campus. This program entails taking three online courses and 300 hours of a school setting internship.
Wright State University, Miami Valley also offers a school nurse graduate certificate program. This program consists of 22 hours of graduate level courses. You must be an RN, have a bachelor's degree, with a GPA of at least 2.7. This program consists of both online as well as campus-based classes. It appears that you must visit the campus in order to receive the certificate, but some of the courses are offered online.
Note- check with each school for accreditation.