Educational data mining (EDM) focuses on solving theoretical and practical problems in education by applying principles and techniques from educational science, computer science, psychology, and statistics. It is believed that EDM will become more mature and promising in the Age of Big Data. This paper aims to help readers to understand or engage EDM research. First, the basic concepts, characteristics and research history of EDM are introduced. Then some latest results of EDM are presented and analyzed. Most results were published in 2013 and later, including some studies on several educational techniques that were rarely investigated before. Those results are also analyzed via classification, statistics and comparison, and based on which strength and weakness of EDM is discussed. Finally, opportunities and challenges facing EDM are discussed.