"OER" and "ZTC" are often used interchangeably but they are not necessarily the same thing. Here's how they're different.
Open Educational Resources (OER) carry an open license. -- Creative Commons - CC which grants permission to access OER materials for free along with the permission to modify the work in the following ways:
ZTC stands for Zero Textbook Cost and is a broad umbrella term for courses where there are no required textbook related costs. These courses may use a combination of openly licensed content, links to scholarly or professional websites, library resources, original content, or other free resources for students. In many cases, ZTC courses utilize a curated collection of many resources rather than a single text.
Some of the learning materials may cost the students zero dollars but a cost is incurred somewhere. For example, materials from Western Library's resources are considered ZTC but not OER. Why?
Apply methods to retrieve data
Demonstrate methods to summarize data
Prepare data dashboards
Analyze historical data
Predict data trends
Interpret statistical data
Use financial evaluation methods
Evaluate optimal solutions
Use data to make business decisions