This study explored the effects of modality, redundancy, and signaling principles in multimedia learning with abstract and concrete representations of an animation on learning in real middle school settings. Based on these principles of the cognitive theory of multimedia learning, ten types of treatment conditions were tested with a pre-test and post-test quasiexperimental design. Data were collected from a large sample (n=826) sample of children with low prior electricity knowledge. Analyses showed that all treatments helped students to develop knowledge of the topic to some extent. However, while the modality effect holds true for middle school students' studying electricity units with a multimedia instruction in real school settings, the signaling and redundancy principles do not hold true. The study also investigated interactions among prior science scores, prior knowledge about the topic, and multimedia treatments. Findings were discussed in relation to similar studies reported in the literature. Finally, the study raised a set of further research questions in the last section.