(off: to go off: to have spoiled like meat that has sat out in the summer sun for a few days)
You may want to try "What was secondary school like?"
"What was your high school like?"
This implies the last three or four years of Secondary school to Americans depending upon the school district. If you wish to add the rest of secondary school "What were middle and high school like?" That starts seven or six years before graduating from secondary school depending upon the school district.
And now I shall go off on a tangent to explain what I just wrote:
American School Districts are political departments ranging in size from town to city to county. Each one can have its own curriculum, holiday schedule, testing policy, division of the grades between schools, etc. all of which are influenced by the voters. They are run by an appointed Superintendent, a central staff, all of whom are supervised by an elected School Board.
Much has been said about this. The best summation is:
"In the first place, God made idiots. That was for practice. Then he made school boards." Mark Twain