This project was designed to test Mayer's multimedia theory in an elementary school to improve students' mathematics learning for low-income children. The study designed and developed two multimedia mathematics experiments in 3rd grade: 9's multiplication experiment and geometric solids experiment. The two experimental lessons were implemented in two 3rd grade classes of low-income children in the United States in January and May 2010, respectively. A one-group pretest-posttest design was used to collect quantitative and qualitative data in both experiments. Both experiments found that the participating teacher and students scored very high respectively; the participating students were very attentive to multimedia mathematics instruction; and the participating students scored significantly higher in mathematics quizzes at posttest at the end of the implementation than at pretest prior to the implementation. The project has theoretical and practical implications for international kindergarten through high school education. (Contains 1 figure and 6 tables.)