I graduated in 1982 and AP classes were around then, but there is another possibility that bypasses AP classes completely.
Anyone can take classes at a community college, regardless of age. As a high school student, Lois could have taken enough credits to enable her to complete her university degree in three years and still graduate high school with her classmates.
Actually, I’ve been told that if enough credits are completed at the community college level (32?) then a GED is automatically earned. It wouldn’t be too much of a stretch to say she received a diploma with her class instead of a GED certificate.
