This article brings theory into practice and demonstrates clearly how to apply commonly accepted language acquisition theories to science lesson plans designed for native speakers of English. In the first section of the article, readers will learn not only how to apply theory to science lessons, but also, and more important, why to apply certain theories to certain types of lessons, moving beyond the limitations of just plain "good teaching." Then, using an everyday science lesson utilizing demonstration and hands-on activity strategies designed for upper elementary students, the authors describe how to adapt objectives for ELLs and how to analyze lessons in order to modify the language demands of the lesson based on the theories. Key points in this process involve increasing interaction and comprehensibility, and prioritizing learning. The procedure includes the adaptation of content objectives, analysis of the linguistic and cultural demands of the lesson, the creation of language objectives, and the modification of assessment procedures.