At three schools in Riga, the morning bell is now followed by something unusual: fifteen minutes of silence, with pupils following a recorded breathing exercise. The trial grew out of a simple observation by a deputy head — that lessons were being lost not to bad teaching but tofrayed nerves, hers and the children's alike. The first term's numbers were modest but real. Teachers reported about a third fewer classroom incidents in the trial term, and pupils' own questionnaires recorded better sleep and less dread about Monday mornings. One boy wrote, in the flat tone of the truly converted, that he now uses the breathing count before assemblies. Parents' evenings, several teachers noted, became noticeably shorter. Researchers remain guarded. The studies are small, short and often written by those who designed the scheme. Placebos are hard to arrange when the pupils know they are the experiment, and a calm term may reflect a mild winter as easily as a new habit. The sceptics' strongest card is history: schools have adopted and abandoned plenty of fads, from brain gym to learning styles. The schools' reply is pragmatic. Nothing was cut from the timetable; no equipment was bought; the exercise simply occupies minutes that were previously spent settling down. F ten quiet minutes cost nothing and change something, the argument is easily won, the deputy head argues. A quiet mind, like a sharp pencil, is a tool for learning. The trial will run two more years, quietly, which is perhaps the only appropriate way.
选词填空：At three schools in Riga, the morning bell is now followed by something unusual: fifteen minutes of silence, with pupils following a recorded breathing ______.