Expository lessons and guided discovery lessons use different implementation strategies to teach students abstractions. Expository lessons are usually more teacher-centered, so the teacher provides much of the lesson�s information as well as clarifying examples. Guided discovery lessons on the other hand are usually student-centered. That is, the teacher provides the students with information and �guides� them to discovering the abstraction on their own. When students discover abstractions on their own, they use and further develop their thinking skills and learning becomes more meaningful. Guided discovery lessons tend to require more time since the redirection used in this strategy often involves more divergent questions get asked during the lesson. As a result, teachers must constantly be �on their feet.� That is, they must constantly be thinking of how they can channel students� divergent responses towards the lesson goal. Additionally, guided discovery lessons may include students learning incidental information (i.e. information not necessarily included in the lesson�s objectives.) This is goes back the fact that guided discovery lessons involve more divergent questions.
As a first time teacher, I feel that I may not possess the teaching experience to successfully carry out a guided discovery lesson during my first year of teaching, mainly because I have a hard enough time judging how much time to plan a simple lesson, much less be able to allot enough time to teach guided discovery lessons. While I feel that guided discovery is more advantageous for the student, I would be afraid that I would not be able to cover all the material I was required to teach. I feel that all of these factors are things that I will learn to judge better once I�m actually in a classroom.
Both expository and guided discovery lessons are planned in roughly the same way. First, identify the topic and consider students� background knowledge. Second, decide exactly what you want students to know, understand or be able to do (i.e. create objectives.) Third, select or prepare examples to use in the lesson that will help your students understand the abstraction being taught. Both positive and negative examples should be taught, with more emphasis placed on the former. Examples should include key characteristics that describe the abstraction being taught. For example, if a teacher was teaching the concept, �Adverb�, he or she should provide example sentences that include adverbs modifying a verb, an adjective, and another adverb. Not providing an example of all possible cases of the concept could result in the student not fully understanding the concept. One example I can think of from back when I was in junior high concerns learning the concept adverb. I remember first learning about adverbs and noticing that just about every sentence the teacher or our workbook had, the adverbs ended in �-ly.� As a sixth grader, I originally thought this was also a characteristic of an adverb. I later learned that adverbs do not necessarily have to end in �-ly� when another English teacher I had used examples of non-�ly� adverbs.
While examples are also helpful and important in expository lessons, they are crucial for discovery lessons, since students are relying mostly on examples given by the teacher in order to discover and learn the abstraction. The order examples are presented can determine how quickly students learn the abstraction (i.e. presenting obvious examples first) or how much more practice they receive in thinking and analysis skills (i.e. presenting less obvious examples first.) Presenting examples in different orders can help keep students interested in learning (i.e. variety).
While the planning phase of expository and discovery lessons are similar, the implementation phases are virtually opposite. Expository lessons start with the teacher writing the abstraction on the chalkboard or overhead. Doing this visually focuses the students on the lesson and allows them to refer back to it at any point in the lesson. From this point, implementation depends on the lesson but usually the concept is defined and then clarified with examples. Discovery lessons, on the other hand, present a series of examples to the students. Students describe each set of examples and compare them with previous sets. Ultimately, the students �discover� the abstraction with the guidance of the teacher and at this point, the teacher writes the abstraction on the board for the class.
While expository and discovery lessons focus on teaching concepts and generalizations, discussion lessons focus on other goals, such as understanding relationships, developing leadership skills, and arriving at a consensus. In discussions, the teacher plays the role of facilitator in that students are more in control of the learning. As a result, it is important for teachers to keep students on task by carefully planning and organizing class discussions.