OER and ZTC are often used interchangeably but they are not necessarily the same thing.
A zero textbook cost course is one that uses learning materials that cost the students zero dollars. For example, materials from Western Library's Databases are considered ZTC but not OER. Why? While the learning materials cost the students zero dollars, there is a cost to Western Library in the form of database subscription fees and other material costs.
Adopting Open Educational Resources (OER) is a common method of eliminating textbook costs in courses. OER carry an open license. This is a type of license (Creative Commons - CC) that grants permission to access, re-use and redistribute a work for free, with few or no restrictions.
If you see an open license symbol like the this one, that's how you know it's OER!
From "Discovering Open Educational Resources (OER)" by Steven Bell.
Re-used thanks to a Creative Commons Attribution-Non-Commercial-ShareAlike 4.0 International License
Link Your Students to Targeted OER Content
One of the benefits of OER is the capacity to link students to a page, section or chapter that addresses the particular competency or skill you are trying to teach by inserting the link on the relevant Blackboard page. Often sections and pages are shorter and more to the point than a traditional text books. Linking in this way is a great way to customize or "remix" OER content that serves your needs.
Examples of open textbook initiatives and curation hubs:
1. OpenStax is a non-profit educational technology initiative begun in 2012 and based at Rice University. The service is web-based and free to adopt, use, and revise due to it's open copyright license. Peer-reviewed textbooks are authored by experts in their fields and updated and revised when it becomes necessary.
2. Open Texbook Library is part of the Open Education Network based in the Center for Open Education at the University of Minnesota’s College of Education and Human Development.
3. Libre Texts curates open content that can be used either directly or as content for building customized remixes.
In addition to the general links below, this page contains examples of OER in each of the programs linked at the left.