The highest rate of vocabulary development (and corresponding acquisition of background knowledge) occurs during the preschool years. This makes preschool a crucial time for effective, content-rich instruction. Accordingly, the Institute has developed a series of Common Core State Standards (CCSS)-aligned modules, which are designed to strengthen the ability of early childhood educators to impart rich, academic content in fun, developmentally appropriate ways. The modules cover the academic domains of oral language development, early literacy, early science, and early mathematics.