I am not affiliated with Harvard. Can I access your digital resources? Does Harvard have reciprocal agreements with other universities for this purpose

Unfortunately, except for the HOLLIS catalog and the Harvard Library web site, almost all online resources of the Harvard Library website are only available to Harvard ID holders (students, staff and faculty), due to the terms of our subscription agreements with online data providers.

There are some publicly accessible collections you can use: Digital Access to Scholarship at Harvard (DASH, an open-access repository of research by members of the Harvard community), Harvard Digital Archives, Hathi Trust, Google Books, and especially the resources listed in the Directory of Open Access Journals.

Some US institutions have more open resources, like the New York Public Library's "The Research Library," described as "a scholarly, university level collection open to the public".

Wikipedia also has a List of Academic databases, some of which have free access -->  https://en.wikipedia.org/wiki/List_of_academic_databases_and_search_engines .

Also note, by searching the web, that there are free online courses offered on most academic subjects, which might be of help to your students.

Best of luck with your teaching and research.