Final answer:
Penn State University joined the Big Ten Conference in 1990 and began competing in the Big Ten Championships in the 1992-1993 school year.
Step-by-step explanation:
Penn State University (PSU) joined the Big Ten Conference in June 1990 and began to compete in the Big Ten Championships during the 1992-1993 school year. This was a significant expansion for the conference, which traditionally had been comprised of Midwestern schools, and marked PSU's transition from independent status to becoming a part of a major collegiate athletic conference.