AFTER A whirlwind seven weeks in office, Prince George's School Superintendent Iris T. Metts opened a critical academic year yesterday with top-to-bottom changes already -- declaring that "it's a new day" for the system. The moment she took office, Ms. Metts said that "there is no excuse for not improving achievement." Showing an intent to deliver quickly, she mounted a campaign that has almost eliminated what had been a serious shortage of teachers. In June the system needed to hire 1,400 teachers; on opening day this week, the system was short 89 teachers, mostly in the difficult-to-fill math, science and special education slots. Also, the rate of hiring provisionally certified teachers has been reduced.

Superintendent Metts has selected four top administrators to press her agenda, which calls for early improvement of state test scores. Out of the central office are 130 administrators, dispatched now to the field or to the classrooms. Ms. Metts seeks to raise the county schools' performance within years from second from the bottom in Maryland to the top 10. Her proposed route to improvement calls for in-school discipline measures to take the place of suspensions; new and renovated classrooms; better communications with parents, other county agencies and local business and civic groups; and more efficient management and accountability. She also has requested -- and so far won -- a unified county leadership of all elected officials behind her efforts.

The turnaround sought by Ms. Metts has got to succeed if Prince George's is to retain its base of public school families who otherwise are poised to move or send their children to other schools in the absence of improvements. So far, it has been anything but business as usual -- and the new momentum is heartening.