Structure drills are especially helpful in teaching basic dialogue. Teachers provide students with simple greetings such as "How are you?" or "I am fine," which students repeat until they memorize them. Teachers can use images or draw pictures on a blackboard to illustrate the meaning of the phrase. For example, to demonstrate what "I am happy" means, a teacher may draw a happy face, or she may draw a sad face for "I am sad." Once the students have learned the meanings of the phrases, the teacher can point to one and prompt students to say the appropriate phrase.
Structure drills mainly help beginner second-language learners. The drills teach students proper sentence structure and pronunciation. They also provide students with a beginning arsenal of sentences and phrases in the language they're learning that they can easily replace with other vocabulary. For example, if a student knows how to express how she's feeling, she can substitute any feeling into a sentence, whether it's "happy," "sad" or "bored."
At a certain point, second-language learners need to progress beyond structure drills and learn more advanced grammatical concepts, as well as the grammar rules behind the sentence structures they've memorized. Language learners can't forever repeat sentences after an instructor and hope to somehow internalize the complexities and nuances of a language. Eventually, second-language learners need to practice the language in a nonartificial setting --- that is, they need to practice conversing naturally in different situations. Natural conversations require flexible dialogue --- even dialogue that sometimes discards structure.
Although structure drills aid learners in absorbing a second language, students shouldn't simply repeat structure drills for the entire class. An effective beginning second-language class starts with a few structure drills that introduce basic vocabulary and sentence structure. The rest of the class then practices the patterns learned using various methods, such as dialoguing with other students or completing individual writing assignments.