Pre-K
The pre-kindergarten class. This is the lowest level of class and it is the class before kindergarten class.
Kindergarten
The class before first grade class. Generally for 5-year-olds, but sometimes includes 4-to-6-year-olds.
First Grade
The class after Kindergarten. The first school year of primary education is referred to as First Grade of Primary.
Second Grade
The second grade forms the second layer of the foundation of a child's primary education. In the second grade, children are usually 7 to 8 years old.
Third Grade
Third grade (also called grade three or primary 3) is a year of primary education in many countries. It is the third school year of primary school. Students are usually 8–9 years old