Once students reach middle school literacy becomes a bit more complicated. For one, students are expected to expand their vocabularies to include technical terms from their different classes. For example, a science vocabulary may include words like energy, chemical, environment, or gravity that have a special meaning in a grade-level science textbook. Unfortunately, students do not always read their textbooks where the definitions and applicability of these terms can be found. Underdeveloped textbook reading skills then become a barrier to success on standardized tests, in high school, and later on in college.