From The Stranger SLOG, Seattle Schools Students Steal Teacher Passwords, Alter Grades.
It appears that some half clever students attached a device, called a keylogger, to teachers' computers. The keylogger, which gets installed between the keyboard and a USB port, records every key stroke on the keyboard. The keylogger can then be read to reveal the key strokes, including IDs and Passwords. Apparently the teachers' ID and Passwords were used to log into the grading system and alter grades.