Many educators understand that lectures are cost effective but not learning efficient, so continue to search for ways to increase active student participation in this traditionally passive learning environment. In-class polling systems, or "clickers", are inexpensive and reliable tools allowing students to actively participate in lectures by answering multiple-choice questions. Students assess their learning in real time by observing instant polling summaries displayed in front of them. This in turn motivates additional discussions which increase the opportunity for active learning. We wanted to develop a comprehensive clicker methodology that creates an active lecture environment for a broad spectrum of students taking introductory physics courses. We wanted our methodology to incorporate many findings of contemporary learning science. It is recognized that learning requires active construction; students need to be actively involved in their own learning process. Learning also depends on preexisting knowledge; students construct new knowledge and understandings based on what they already know and believe. Learning is context dependent; students who have learned to apply a concept in one context may not be able to recognize and apply the same concept in a different context, even when both contexts are considered to be isomorphic by experts. On this basis, we developed question sequences, each involving the same concept but having different contexts. Answer choices are designed to address students preexisting knowledge. These sequences are used with the clickers to promote active discussions and multiple assessments.