The document discusses building background knowledge and academic vocabulary for science units. It recommends creating a "Science Working Word Wall" at the beginning of each unit to introduce new vocabulary words that are important for students to know and understand. The word wall should include tools, unit-specific words, and properties. Introductory activities for the word wall include having students make predictions about what vocabulary words are used for and classifying related words. These activities aim to develop students' vocabulary, oral language, and connections between words and concepts.