Earth Rocks! is a collection of online educational videos, geared toward introductory-level oceanography and physical geology lectures and labs. This creative-commons-licensed collection currently contains 65 videos, each focusing on a particular topic and ranging from 2 to 20 minutes in length. The videos incorporate a range of educational video design principles, including student pacing control and embedded assessment, and are available through the Earth Sciences Department website at City College of San Francisco (CCSF) and Earth Rocks! YouTube channel. As these videos are part of active courses at CCSF, and feedback is continually gathered, they are regularly updated to fix errors or misunderstandings and improve overall educational value and content coverage. Initial video development was motivated by a desire to improve student preparation for class activities and discussion, when the textbook was left unpurchased or unopened. Paired with pre-class assignments and quizzes in a flipped-class model, we were immediately able to engage in more active learning, critical thinking, and problem solving in the classroom. We have also found the videos useful as exam- and skills-review opportunities for all our students, and they've been a boon for English-as-a-second-language students and students with weak basic skills, who can review the videos as slowly and frequently as needed. These videos have been in use at CCSF since Fall 2012, and we have 3.5 years of data on student likes and dislikes and frequency of use. We also can show correlations with student learning outcomes achievement, retention, and reduction in the gap between high- and low-performing students. http://www.ccsf.edu/earthrocks