Visualization is central to thinking in science and engineering. Kekule’s visualization of the Benzene ring advanced the theory of chemical structure. Tesla, Einstein, and Feynman reported that visual imagery was central to their thinking. These visualizations existed in the minds of scientists; they were internal visualizations. External visualizations such as diagrams, graphs, scientific visualizations, and simulations also play an important role in science. These visualizations exist in the world, printed on paper or presented on computer monitors. Advances in computer graphics are constantly increasing the power of these visualizations to model complex natural phenomena. Despite the importance of visualizations in science, students are rarely taught to visualize or to critically evaluate how to best use external visualization techniques in scientific thinking. Research presented in this symposium will provide insights into how to train internal visualization skills and capitalize on external visualizations in science, technology, engineering, and mathematics (STEM) education. Presenters will discuss relations between internal and external visualizations in scientific domains such as physics, geoscience, ecology, and chemistry. They will report new basic research on the brain bases of internal visualization and how the visualizations of scientists differ from those of artists. Finally they will examine how to best engage students in scientific thinking with powerful external visualizations.