Most of the research on motivation in education often uses measures taken outside the context of students' actual learning activities. This paper, however, maintains that students' motivation and learning are situated. Using a diary technique, this study explored how a class of high-achieving students in an Australian state high school (N = 34) appraised continuously their mathematics lessons. Both qualitative and quantitative data were generated. Students' diary comments provided descriptive evidence showing how students' different types of self-knowledge interplayed with situation-specific learning demands. Based on these diary comments, students' ratings of various motivational constructs were classified into motivating, unmotivating and neutral groups. ANOVA Tests with Scheffe Post Hoc Tests found motivational differences in lessons perceived as motivating versus those perceived as unmotivating. A subsequent discriminant analysis showed that a mastery goal, task values and a mastery-oriented learning climate were important predictor variables that discriminated motivating lessons from unmotivating ones. In short, the current findings provided empirical evidence regarding the dynamic and interactive aspects of motivation and learning in a classroom context. (Contains 6 tables.)