In 1947, a professor at the University of Chicago, Dr. Chandrasekhar, was scheduled to teach an advanced seminar in astrophysics. At the time he was living in Wisconsin, doing research at the Yerkes astronomical observatory. He planned to commute twice a week for the class, even though it would be held during the harsh winter months.
Registration for the seminar, however, fell far below expectations. Only two students signed up for the class. People expected Dr. Chandrasekhar to cancel, lest he waste his time. But for the sake of two students, he taught the class, commuting 100 miles round trip through back country roads in the dead of winter.
His students, Chen Ning Yang and Tsung-Dao Lee, did their homework. Ten years later, in 1957, they both won the Nobel prize for physics. So did Dr. Chandrasekhar in 1983.
For effective teachers, there is no such thing as a small class.
From Illustrations for Preaching and Teaching from Leadership Journal - Craig Brian Larson. Baker Books, Grand Rapids, MI, 2000. Page 254.