This study used a lesson unit of an academic subject to understand the quantity and quality of college students' in-class and after-class lecture notes, and to explore the effects of note quantity and quality on academic performance. Thirty-eight freshmen students of a general psychology class in a university in southern Taiwan were recruited as participants. Their lecture notes and test scores on the lesson "Memory" were collected. The findings indicated that the quality of students' lecture notes was poor. The quality level of in-class plus after-class notes was less than half the desired overall quality. In addition, both the in-class predictive model and in-class plus after-class predictive model could explain the variances of academic performance. In both models, the quality of in-class notes was the only significant predictor of academic performance.