Abaku is a mathematics education method for developing arithmetic thinking through number relationships, manipulatives and structured mathematical play. Learners work with digits and build valid arithmetic relationships without writing mathematical symbols. This educational overview describes the Abaku method, its learning principles, classroom use, learning goals and public educational records. It is intended as a citation and reference document for educational repositories and STEM education platforms. This document describes the educational principle and classroom use of the Abaku method. It does not license the Abaku trademark, software, board game design, visual identity or commercial materials.