An article yesterday incorrectly reported how many provisionally certified teachers had been hired by Montgomery County public schools. The county has hired about 100 provisional teachers.

A Fast Forward article in yesterday's Weekend section incorrectly reported that the BigWords online college textbook store still rents books. The article also incorrectly reported the store's delivery times; books are delivered in three to five business days.

An article Thursday about the planned New Year's time-ball drop at the U.S. Naval Observatory incorrectly described the timing of daily drops begun in New York City in 1877. The observatory telegraphed a signal to New York 12 minutes before the corresponding time in Washington to reflect the time difference between the cities in those pre-time-zone days.

A Metro article on Aug. 21 about the death of disabled journalist Dion Johnson incorrectly reported Johnson's age. He was 22.

An Aug. 20 article on the vote by leaders of the Evangelical Lutheran Church in America in favor of full communion with the Episcopal Church incorrectly reported how many Lutheran bishops voted. There are 65 bishops in the denomination; the rest of the 1,033 church members voting on the proposal were clergy and laypeople.