David-Paul Sip
Correct Admiral. My bad, I misread/misunderstood your post. I thought you were talking about when they eliminated OACs. Grade 13 was before my time and I only new OACs.
"The Ontario education system had five years of secondary education, known as Grade 13 from 1921 to 1988; grade 13 was replaced by OAC for students starting high school (grade 9) in 1984. OAC continued to act as a fifth year of secondary education until it was phased out in 2003."