Effective teaching methods may be constrained by school curriculum, but educators can still devise instructional approaches based on the needs of their students. Some courses are taught better through lecture, while others may require class participation and direct interaction through laboratory and field-trips. Two common teaching methods are known as top-down and bottom-up, which take opposite approaches to providing students with an education.


A top-down teaching style focuses on providing students a large view of a subject, immersing them in the big picture without explaining the components that make up the subject. For example, in an English as a Second Language class, a top-down approach would begin by immersing students in all aspects of learning English immediately, including writing, reading and pronunciation. Students would not be taught the intricacies of vowels, nouns and pronouns first, instead they would be plunged into the totality of learning English and then gradually learn the building blocks that make up the English language.


Unlike a top-down teaching approach, which takes a macro view of a subject first, a bottom-up teaching approach begins with the component parts of a subject, and gradually builds up to the whole. For example, in an ESL class, a bottom-up approach would begin with things such as phonics, letters, vowels and syllables, which are the building blocks of language. It's only after students have mastered these specific rules and systems that they move on to speaking and reading.


Top-down and bottom-up teaching methods have the same learning objectives but different ways of achieving them. Top-down teaching is concerned with motivating students to learn through direct interaction and immersion, and allowing them to find meaning in a subject by applying their own experiences. Bottom-up teaching is more instructor-driven and focuses on the minutia of a subject as a way of decoding and simplifying each component through repetition and memorization.


Because top-down teaching emphasizes instruction through context and relies in part on a student's background and experience to acquire knowledge, it may not provide the same level of specific subject skills as a bottom-up teaching approach. Conversely, though a bottom-up teaching approach will strengthen a student's grasp of a subject's fundamentals, it's lack of emphasis on learning within the context of a larger whole may limit its effectiveness. For example, students who learn the specific meaning of a word may not understand how the meaning of that word changes based on the culture where the word is used.