grade-by-grade的意思

grade-by-grade是什麼意思啊??

其意是 . [按照一定的次序與步驟逐漸推進學習 ]
循序漸進, 循級[學期]而進步階段地求學 .
Ex;
All of students graduated from their elementary school were belonged
. to be the grade by grade in the terms of six of years
.小學畢業的學生是屬於6年學期循級而進步階段地求學 .

without sentences around it, it is hard to get a firm idea what it really means. It can be for students or teachers.

grade by grade - 每級對照。