She was enrolled there, but missed the first three weeks of classes. What is your source that she only took correspondence courses? That seems very strange and unlikely to me. This is the University of Washington, in 1961. Correspondence courses? Really?
“The real purpose of this trip, however, may have been different than Stanley Ann Dunham described to her friends. In August, 1961, she enrolled in a University of Washington extension course. Between August, 1961 and March 1962, she enrolled in a total of four extension courses at the University of Washington, earning a total of 20 credits for her work in those courses, no small feat, considering that graduation required 180 credits, and the typical full time student earned 45 credits a year. Neither Box nor Blake has any recollection of Stanley Ann telling them she was enrolling on that same trip in extension courses at the University of Washington. (40)”
http://www.christianfaithandreason.com/obama7.html
I may wrong in assuming that extension courses are correspondence courses.