Abstract: In mathematical problem solving, students may make various errors. In order to draw useful lessons from the errors, and then correct them, we surveyed 24 eighth-grade students’ performances in geometrical problem solving according to Casey’s hierarchy of errors. The paper also discussed that (1) students’ motivations and beliefs can lead to errors at the stage of comprehension, strategy selection, and skills manipulation; and (2) students’ geometric schemas also influenced their strategy selection.

Key words: Geometrical problem solving; Motivations; Beliefs; Schemas