Crossword puzzle clue "school's first stage"

School's first stage?

Elaborate Broadway stage decor, vis-a-vis summer camp theater stage design?

At an early stage — at a late stage

Film character whose first line is "First day of school!"

Middle school stage, commonly

First word across in the first-ever crossword (1913) and the first of a dozen appearances of the word in this puzzle's grid, written word search-style (left, right, down, and diagonally) ... Can you f