Believe it or not, in 1951 I "tested out" of kindergarten.I remember one question on the test. It was a picture of a girl holding a purse. The question was, which hand is the purse in, her right or her left.
You had to know which side was right, then turn it around because the girl was facing you.
Anyway, I started first grade a year early.
I am of the opinion that grade qualification testing should be condidered each year in elementary. There are a lot of 3rd graders who still lack 2nd grade math or reading or science skills.