The Suuji Approach to Multi-Digit Addition: Using Length to Deepen Students’ Understanding of the Base 10 Number System

We describe the Suuji representation of numbers which aims to deepen elementary students’ understanding of the base 10 system. (“Suuji” means “number” in Japanese.) This representation takes a two pronged approach of (1) making the place value more explicit and (2) using length to represent numbers, thus allowing students to reason spatially. We taught multi-digit addition using the Suuji representation to 20 second and third grade students. The article uses lesson descriptions and student work to illustrate the Suuji approach, as well as its impact on student learning.