Quantum mechanics allows particles to potentially tunnel through energy barriers which classical mechanics forbids. The scanning tunneling microscope (STM) uses two conductors -- a platinum-irriduim tip and a sample -- to set up a potential difference. Air between the two conductors represents a potential barrier which classical mechanics forbids particles (electrons in this case) to cross; however, because of the tunneling probability, a current exists between the conductors through the air. The STM can image the sample using one of two modes: the constant height mode keeps the tip at a constant height above the sample, imaging the changes in the tunneling current; the constant current mode keeps the tunneling current constant while moving the tip to follow surface features. In this experiment, the student uses a Burleigh STM first to image a gold diffraction grating to calibrate the maximum scanning range of the STM, then to image a sample of highly oriented pyrolytic graphite (HOPG) to determine the bond length and angle of the carbon atoms. First using the constant current mode, the student images the gold diffraction grating with a know grating specification of 2400 lines/mm to find the maximum scanning range of the STM. Then, the student prepares the HOPG sample by cleaving it with transparent tape. Finally the student images the HOPG using the constant height mode to find the bond lengths and angles of the carbon atoms in the sample.