Many students who have the ability to succeed in science, technology, engineering and math (STEM) disciplines are often alienated by the traditional instructional methods encountered within introductory courses; as a result, attrition from STEM fields is highest after completion of these courses. This is especially true for females. The present study examined the use of teacher-designed multimedia within an introductory biology course. A mixed-methods approach was used to assess the relationship between the use of multimedia and the amount of information students comprehended when learning photosynthesis in a real class setting. Also, the relationship between the use of multimedia and learning gains of females was examined. It was determined that multimedia significantly increased learning gains of female students compared to the use of static pictures and text. In addition, preliminary indications are that multimedia had the greatest value for second-tier students with lower prior knowledge levels, and this was often females.