New approaches for teaching and assessing scientific inquiry and practices are essential for guiding students to make the informed decisions required of an increasingly complex and global society. The Science Skills approach described here guides students to develop an understanding of the experimental skills required to perform a scientific investigation. An individual teacher's investigation of the strategies and tools she designed to promote scientific inquiry in her classroom is outlined. This teacher-driven action research in the high school biology classroom presents a simple study design that allowed for reciprocal testing of two simultaneous treatments, one that aimed to guide students to use vocabulary to identify and describe different scientific practices they were using in their investigations--for example, hypothesizing, data analysis, or use of controls--and another that focused on scientific collaboration. A knowledge integration (KI) rubric was designed to measure how students integrated their ideas about the skills and practices necessary for scientific inquiry. KI scores revealed that student understanding of scientific inquiry increased significantly after receiving instruction and using assessment tools aimed at promoting development of specific inquiry skills. General strategies for doing classroom-based action research in a straightforward and practical way are discussed, as are implications for teaching and evaluating introductory life sciences courses at the undergraduate level. [Contains supplemental material, which can be found at: http://www.lifescied.org/content/suppl/2014/02/12/13.1.90.DC1.html.]