A teacher at a Northwest Miami-Dade middle school is under investigation for ordering a student into a storage closet as punishment Tuesday, according to the county school district.

The teacher at Lawton Chiles Middle School, 8190 NW 197th St., has been reassigned to administrative work at the school's front office while Miami-Dade schools police investigate, said district spokesman Mayco Villafaņa.

The incident happened in a portable classroom equipped with a four-by-six-foot storage closet. The closet, which has a locking door, is used to isolate unruly students from the rest of the class, Villafaņa said.

''It was used by the teacher as a timeout area,'' he said.

While the seventh-grader was inside the closet, a second student reported the punishment to a staff member, who relayed the information to the school's assistant principal -- who then accompanied a school police officer to the portable.

''The assistant principal heard a knocking from the closet, and asked the teacher to unlock the door,'' Villafaņa said. The student was still inside. It was unclear who had locked the closet, he said. The door can be unlocked from inside or outside.

Another teacher at Lawton Chiles Middle who reportedly used a closet as punishment will also be questioned, Villafaņa said.

This is the second time in recent days that classroom discipline has come under scrutiny. A teacher and a volunteer aide at Coral Gables Elementary School were arrested and charged with child abuse last week for allegedly taping first-graders' mouths and limbs.

Miami-Dade Public Schools' staff handbook states that ''timeout rooms'' are acceptable forms of ''alternative control,'' but doesn't elaborate.

Villafaņa said the closet, outfitted with a desk and books, wasn't just used for punishment.

''Some of the students actually ask to be placed in there so they can concentrate on a reading assignment,'' he said. ``We're looking at whether this is the most positive way of teaching and educating students.''