American Grades in schools

[mynx]

Can someone please tell me what ages correspond to what grades in American schools?

[Clanad]

Most children enter first grade at age 6 or 7 depending on state law and in which month their birthday falls.  For each succeeding year their age increases one year, i.e., 3rd grade would be 8 or 9.  The grades are K through 12 with K being kindergarten and 12 being a senior or last grade in high school before graduating. Most graduates are 18, although some are as young as 17, which I was.  Kindergarten is not generally recognized as a "grade" and some states do not require kindergarten attendance.  The parents have the option of enrolling children is several choices of pre-school classes, but this is, usually, at their own expense and not part of the public school system...