Since 1990, environmental education (EE) has become more integrated into K-12 education through EE programs. A synthesis of research identified overall themes, outcomes, benefits and challenges surrounding research integrating outdoor learning into mandatory curriculum. Most research on outdoor classroom focuses on student development, attitude, and knowledge changes along with teacher factors for adaption. Students engaged in outdoor learning have more positive attitudes toward school, feel more responsibility and ownership over school work, demonstrate improved confidence and self-esteem, and improved achievement in testing. More research should be conducted surrounding students daily student behavior and achievement after participating in outdoor classroom learning.