I'm of the same vintage and I believe I read the same series of biographies for book reports -- probably in the 4th or 5th grade. These books were published circa the early 1960s (or maybe earlier) and featured b&w line drawings illustrating the person's life. The covers featured the same artwork, and the background color for each book jacket was a different color. I remember reading the book on Eleanor Roosevelt (blue/gray, I think) and the one on Abe Lincoln (tan). Amelia Earhart was also in the series.