All the science classrooms are on the ground floor; the other subjects are upstairs.
Explanation:
A semicolon indicates a pause between two clauses and a clause is a statement that can stand alone and make sense. "All the science classrooms are on the ground floor" and "The other subjects are upstairs" are both independent clauses and can stand alone, therefore you can add a semicolon in between in order to limit the use of transition words.
