Grade 12

The Ontario Academic Credit or OAC ( or ) was a fifth year of secondary school education that previously existed in the province of Ontario, Canada, designed for students preparing for post-secondary education. The OAC curriculum was codified by the Ontario Ministry of Education in Ontario Schools: Intermediate and Senior (OS:IS) and its revisions. 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.

Twelfth grade, Senior year, or Grade 12 are the North American names for the final year of secondary school. In most countries students then graduate at age 17 or 18. In some countries, there is a thirteenth grade, while other countries do not have a 12th grade/year at all. Twelfth grade is typically the last year of high school.