The purpose of this study was to investigate the facets of classroom assessment. Case study was adopted with classroom observations, interviews, and document analysis. Three facets were found: 1. activating learning: In language art classes, the teacher effectively made use of learning resources, chose suitable assessment technique, embedded assessment within teaching, and amended scoring rubrics in accordance with students' reactions; 2. misconception: In mathematics classes, the teacher, with a lack of pedagogical content knowledge, was limited to stereotypical assessment method, and even misguided students' learning; 3.myth: In social science classes, the teacher had unrealistic expectation of assessment, and fun did not bring up students' learning. Finally, the researchers raised discussions and reflections for future studies.