ABSTRACT
This chapter discusses what kind of mathematics students learn by practising abacus operation intensively. It looks at an instance of the change in the nature of skills-what used to be instrumental for other goals become an autonomous domain of expertise. The chapter focuses on the shift from intermediate to expert and concerns the process from beginner to lower intermediate. It discusses abacus skills from an instructional perspective. The chapter clarifies the nature of abacus operation as a form of non-school mathematics or a barely legitimatized component in the current curriculum of mathematics education. It examines whether knowledge of how to do calculation on an abacus can be transferred to the paper-and-pencil mode and whether it can help to remove bugs in the written calculation algorithm. Amaiwa tried to apply a simplified version of the "mapping instruction" between abacus operation and written calculation and found that it did not work well.
