While you were trying to pass Poetry 101, Cornell seniors Le Zhang and Michael Lathrop were creating an apple-polishing Lego robot that automatically erases your prof's chalkboard. A final class project, the toady mech uses an Atmel brain, accelerometers for direction control, microswitches to sense the edge of the board, magnets to stay attached and hot glue to keep the Lego from flying apart. As the video below the break shows, it first aligns itself vertically, then moves to the top of the board, commencing the chalk sweeping and turning 180 degrees each time its bumpers sense the edge. The duo are thinking of getting a patent, and a commercialized version would allow your teacher to drone on without the normal slate-clearing pause. So, if designing a clever bot and saving their prof from manual labor doesn't get the students an 'A', we don't know what will.