noun
second year of elementary school; second grader
Abbreviation of 小学校２年(生). Used in casual or note-form contexts to refer to the grade or the student.
うちの子は今年小２です。
My child is in second grade this year.
小２の算数はかけ算から始まる。
Second-grade math starts with multiplication.
Full formal term for a second-grade elementary school student; 小２ is the abbreviated form used in casual or written shorthand.
Abbreviation of 小学校 (elementary school) + ２年 (second year) or ２年生 (second-year student).