A Dutch researcher has looked at the kind of language skills that young children need to be successful in their classrooms. Lotte Henrich's April, 2010 doctoral thesis at the University of Amsterdam, entitled Academic language in early childhood interactions. A longitudinal study of 3- to 6-year-old Dutch monolingual children, looks at the kinds of language used in classroom settings and compares it to the language demands that young children encounter in their lives outside school.
What Henrich calls "academic language" is the language used by teachers as early as preschool to provide instructions and convey information. It is more complex than casual language, with more difficult words, conjunctions, and clauses. Proficiency in this kind of language enables children to understand instructions from their teachers and to show that they have understood what is being taught in class.