The advent of computer-assisted language learning (CALL) materials has revolutionized teaching as increasing numbers of educators realize the power of the medium. With the proliferation of these materials comes a need for developers to make informed choices about the materials they create. In studies using traditional print materials, researchers have discovered the importance of glossing difficult vocabulary words; however, the method of glossing varies greatly. More research is needed to inform the decisions educators make about the types of glosses to offer. The research questions shaping this study are: 1) Does a multiple-choice option that requires students to expend mental energy when discovering the meaning of an unknown vocabulary item increase retention of the word meaning? 2) Do students make use of provided vocabulary definitions when answering comprehension questions containing the target words? 3) Do students interact with an on-line reading passage in predictable ways? Results show that both the traditional glosses and the multiple-choice glosses were effective for learning vocabulary; however, neither method was superior to a degree that is statistically significant. This study aims to understand the purposes with which the students approached the text.