Highest Grade Attended

I was hoping to find more information some day on Grandma Arnold's education level.  Her younger sister Ethel's pic is included in a Thawville High School graduation photo; and I was hoping to find her graduating photo also.  But this census reports that Grandma's highest grade level was eighth. Second column from the right.  Grandma and Grandpa both made it through eighth grade, Frances is in third grade in 1940, and Dad has yet to start school. 

--Federal Census. 1940.