Two disparate research programs have addressed the challenge of instructional multimedia design. One, based on cognitive load theory, has focused on ways of reducing unnecessary cognitive load during instruction to free up resources for learning. The other, based on constructivism, has centered on interactive multimedia, allowing students to build their own knowledge. Attempting to build on both bodies of literature, in this study, we investigated techniques that can raise the useful cognitive load engendered with linear multimedia. Participating online from home, students were pre- and posttested around a short multimedia intervention that explained Newton's first and second laws. In Experiment 1, students who watched a video dialogue involving alternative conceptions reported investing greater mental effort and achieved higher posttest scores than students who received a standard lecture-style presentation. In Experiment 2, two additional multimedia treatments were evaluated to assess the role of instructional time and the method of addressing alternative conceptions. In all, 272 students participated in the experiments. Interviews suggest that students adopted a more active approach to understanding the material if alternative conceptions were raised. In addition, students who watched the dialogue judged themselves to be similar to the student in the multimedia. (Contains 3 tables and 1 footnote.)