This protocol guides the What Works Clearinghouse's (WWC) systematic reviews of evidence on interventions to improve the science, technology, engineering, and mathematics (STEM) knowledge and skills of students in preschool (PK) to grade 12 (or ages 3-21). To conduct the systematic review, use this protocol in conjunction with version 4.1 of the "WWC Standards and Procedures Handbooks" and the "Study Review Protocol." This review focuses on educational interventions, particularly on improving STEM knowledge and skills of children and students in preschool through grade 12. STEM knowledge and skills are critical to students' academic achievement and setting them on a path to high school completion and readiness for college and careers.