<p>This qualitative study was conducted to understand the instructional strategies used by high school integrated STEM (iSTEM) teachers to apply real-world problem solving in their classrooms in the state of Indiana. The problem addressed by this study was the need to understand the instructional strategies employed by iSTEM teachers in their classrooms. Using a basic qualitative approach, data was collected through teacher interviews, classroom observations, and documents. The thematic analysis revealed several themes: (a) there is no single instructional strategy, but teachers adapt their strategies to the context, (b) the importance of preparation using various sources and building on student’s prior knowledge, (c) a focus on asking "why" questions as a priority, (d) the necessity of making group work tangible, (e) the use of modeling as a common strategy, including data collection and analysis, sketching and documentation, (f) the promotion of student independence by being aware and performing tasks independently, (g) the integration of real-world issues to relate learning to student lives, and (h) the challenges posed by time and diversity of student abilities. These findings suggest that iSTEM teachers should be flexible in their approach and emphasize preparation, questioning, modeling, group work, and real-world connections to improve student learning in an integrated STEM approach. The findings contribute to the existing literature on iSTEM teaching and have implications for iSTEM teachers, school administrators, and policymakers. The findings of this study can inform professional development programs for iSTEM teachers and can help school administrators design collaborative and problem-solving learning environments. Lastly, policymakers can use the findings to develop policies that promote the integration of real-world problem-solving into STEM education, thereby contributing to the development of a workforce that is prepared to meet the challenges of the 21st century.</p>