Teachers demonstrate activities because they know best how they want them completed. A common practice in classrooms today is modeled instruction, which provides students with an explicit demonstration of a target skill. This idea of "let me demonstrate" creates a collaborative tone in the classroom between teacher and student. For example, literacy teachers talk their students through their thinking process when teaching reading strategies. They read a portion of a text, pause and "think aloud," speaking the thoughts that led to understanding the reading. Such thinking skills are not innate in everyone, so such modeling gives struggling students a look into a formerly hidden process.
Demonstrating activities is especially beneficial for students with learning difficulties. For example, many students have learning problems involving attention spans, processing and memory retrieval. When teachers clearly demonstrate an activity, these students get a clear representation of what they're supposed to do. Likewise, when teachers have everyone participate in the demonstration by doing the activity along with them, students with learning problems get multiple ways of processing the new information. Additionally, the teacher can demonstrate the links between a skill such as reading and a subskill such as using context clues for understanding. As such, students with cognitive difficulties are less likely to get lost.
Learners who speak English as a second language benefit from modeled instruction for many of the same reasons as students with learning problems. However, ESL students often rely directly on demonstration to know what to do; they might not understand oral instructions due to limited English or increased time needed for processing a non-native language. Explaining the demonstration also allows the teacher to model new vocabulary and sentence structures related to the concept. Finally, ESL learners need to hear a lot of fluent English to build their own linguistic skills. When the teacher demonstrates the use of a reading strategy, for example, ESL students get the added benefit of hearing fluent language.
A desired effect of modeling an activity is showing students acceptable behavior. Teachers demonstrate exactly how the activity is supposed to go. As such, students have direct understanding of what the teacher expects and, therefore, little leeway for deviation. Demonstration for purposes of classroom management works well when teachers model all behaviors of day-to-day classroom activities. Teachers who do this demonstrate everything in the beginning, such as listening to classmates and waiting to be called on. When teachers are ready to introduce more complex activities, students already know what appropriate classroom behavior looks like.