Comprehensive U.S. Department of Education database for education, indexing journals & magazines, as well as books, videos, conference papers and technical reports. Links to full text documents.
Access to mathematical literature, indexing thousands of journals, books and conference proceedings. Via the EBSCOhost platform, rather than the American Mathematical Society platform.
Free, open-source math modeling and simulation tools - for teachers to use in building lessons, or for students to learn in creating and exploring their own models
This resource at GeoGebra specifially implements a lot of the Open Middle activities online, and introduces some other "open middle" math problems as well.
Mathematical activities for all grades that have an "open middle" -- multiple viable approaches for solving the same problem or completing the same task.