Working collaboratively, students explore the effect of different types of DNA mutations using dice. The exercise provides students with a tangible way of visualizing how mutations may contribute to genetic diversity and the randomness with which they may occur. After the exercise, students comprehend better why some mutations may cause devastating phenotypic effects, while others have no effect on the resulting protein. It is an ideal exercise for instructors who are new or inexperienced in using group activities in their classes or by those who would like to expand their repertoire of biology exercises. This demonstration can easily be done in a large lecture hall or in a laboratory setting.