DNA and RNA are composed of nucleotides, which are combinations of nitrogenous bases, pentose sugars, and phosphate. This interaction provides students with practice in constructing these nucleotides and allows students to become familiar with the naming conventions of these molecules. The interaction may be used on a stand-alone Web page or may be incorporated into the content of a website. It is a nongraded activity in which the student builds multiple, different nucleotides each time they access the activity. The interaction may be used in the classroom or may be provided to students as an online activity.