Science, Technology, Engineering, and Mathematics (STEM) is a term seen almost daily in the news. In 2009, President Obama launched the Educate to Innovate initiative to move American students from the middle to the top of the pack in science and math achievement over the next decade (The White House, n.d.). Learning about the attributes of STEM and how they are connected can help promote innovation (Holt, Colburn, & Leverty, n.d.). Teachers involved in STEM education must take the challenge of learning more about the STEM areas and begin showing students how they are connected. To begin this transformation, the author asserts that teachers must become STEM Thinkers who can show their students how STEM is involved in most of the products and systems they use in their daily lives. STEM Thinking can be defined as "purposely thinking about how STEM concepts, principles, and practices are connected to most of the products and systems we use in our daily lives." At the collegiate level, STEM education encourages students to pursue STEM careers in order to meet the growing need for trained professionals in these areas. The focus of this article is on teachers at the primary and secondary levels (i.e., P-12) who are involved in teaching about one or more of the STEM areas in their classrooms. These teachers, who come from a variety of STEM education areas, are typically involved in using hands-on and inquiry-based learning strategies that challenge students to solve real-world problems and explore their curiosities of the natural and human-made worlds. In today's schools, teaching about STEM can take place in many general education and career and technical education subject areas such as agriculture, science, health, technology and engineering, and family and consumer science. This article begins by explaining why it is important for teachers to become STEM Thinkers. It goes on to provide background on the term STEM and STEM education. Next, becoming a STEM Thinking teacher and the components of STEM are discussed. This is followed by a discussion of inquiry-based learning strategies used by STEM Thinking teachers and how STEM Thinking teachers can put STEM Thinking into action in the classroom.