The on-line "Rare Earth Elements and Sustainability" module is designed for use in introductory university environmental science, sustainability, earth science, and physical geography courses. The module can be used as a stand-alone resource, or the module can be used in conjunction with classroom use of the Rare Earth Element (REE) Activity in Unit 2 of the no-cost Interdisciplinary Teaching About Earth for a Sustainable Future (InTeGrate) Mineral Resources module. Specifically, "Rare Earth Elements and Sustainability" can be used prior to classroom use of the InTeGrate activity or as homework after use of the InTeGrate activity. To facilitate multi-institution use, content and assessment are delivered through the Easygenerator learning management system. Placing the InTeGrate REE activity in a broader context, the on-line module highlights the challenges involved in finding substitutes for REE's in consumer electronics and green technologies as well as the possibility that REE reserves will be depleted in the decades ahead. Learners using the module explore both technical hurdles impeding the recycling of REE's and recent innovations in REE recycling. They also examine ways to (a) reduce REE use and (b) reuse products containing REE's. Finally, learners examine the possibility that REE's will be mined on other bodies in the solar system in the future.