form

attributive, from the noun ‘form’ | ‘form’: one of the numbered classes into which the pupils of a school are divided according to their degree of proficiency (“form, n.” OED); ‘first form’ = first year of secondary school; ‘second form’ = second year of secondary school

“The teacher taught from primer to — even taught at times first form high school.”

“That was what they call a continuation school where they taught first form and second form high school. Then you had to go to Kingston for the next.”