Spatial thinking--such as visualizing the earth rotating--is crucial to student success in science, technology, engineering, and mathematics (STEM). Since spatial thinking is associated with skill and interest in STEM fields (as well as in other areas, such as art, graphic design, and architecture), the immediate question is whether it can be improved. While some students are better at spatial thinking than others, everyone can improve. The need to develop students' spatial thinking is currently not widely understood. The author stresses that educators already have some excellent techniques for developing it, through practice, language, gesture, maps, diagrams, sketching, and analogy. Systematically building these techniques into the curriculum could yield important dividends for American education. In this article, the author offers some suggestions on how to foster spatial thinking. (Contains 57 endnotes.)