Though science teachers use a range of curricular materials, the nature of freely-accessible materials for science classes has been a focus of little prior research. In this study, Open Educational Resources (OER) that can be accessed through the OER Commons platform were examined in terms of their characteristics and use using public Internet data mining methods. 8,937 life science, physical science, and applied science resources were evaluated in terms of their material type, grade level, license type, number of endorsements by approved organizations (e.g., a state department of education), alignment with the Next Generation Science Standards, and number of views. Many resources were readings and laboratory investigations, suggesting that teachers may turn to TeachersPayTeachers to address specific, targeted curricular needs. Most resources were for post-secondary science classes, though many were intended for high school, middle school, and elementary classrooms. Relatively few resources were endorsed, and fewer still were explicitly aligned with the NGSS, suggesting the need for greater alignment of standards across states. To provide a richer set of accessible curricular resources for educators, several implications for practice and policy are considered.