Students encounter a number of problems when learning how to Gram stain and view bacterial cells. During the staining procedure, bacterial cells tend to be washed off the slide. Students then have difficulty locating bacterial cells on the slide, particularly the lightly colored (pink) gram-negative cells. Additionally, students often over-decolorize the cells, such that gram-positive cells, which should appear purple, are stained pink instead. This is particularly an issue when older cultures of bacteria are used for the staining procedure (Magee et al., 1975).