to understand what students are thinking prior, or in response, to instruction. These strategies include various forms of "real type" feedback, which can involve the use of colored cards or electronic survey systems (clickers). Another approach is typified by the strategy known as just-in-time teaching. Here students are asked various questions prior to class, the instructor uses these responses to adapt his or her teaching to the students' prior knowledge and misconceptions. Finally, there is a more research-intensive approach that involves interviewing students for the purpose of generating the items that will make up a concept inventory or other forms of diagnostic instruments. Concept inventories require intensive validation efforts. Perhaps the most influential of these concept inventories to date has been the Force Concept Inventory (FCI). Concept inventories can be particularly helpful in identifying difficult ideas that serve as a barrier to effective instruction. Concept inventories in natural selection and basic biology have been developed. While not all the published diagnostic instruments have been developed as carefully as some concept inventories, some two-tier diagnostic instruments (which offer multiple choice distractors informed by misconceptions research, and then ask learners to give reasons for their choices) have been through rigorous development. In identifying students' misconceptions, first teachers can identify their preconceptions. "Teachers need to know students' initial and developing conceptions. Students need to have their initial ideas brought to a conscious level." However, teachers' ability to diagnose misconceptions needs to be improved. When confronted with misconceptions about evolution, they only diagnose approximately half of these misconceptions. Addressing student misconceptions A number of lines of evidence suggest that the recognition and revision of student misconceptions involves active, rather than passive, involvement with the material. A common approach to instruction involves meta-cognition, that is to encourage students to think about their thinking about a particular problem. In part this approach requires students to verbalize, defend and reformulate their understanding. Recognizing the realities of the modern classroom, a number of variations have been introduced. These include Eric Mazur's peer instruction, as well as various tutorials in physics. Scientific inquiry is another technique that provides an active engagement opportunity for students and incorporates metacognition and critical thinking. Success with inquiry-based learning activities relies on a deep foundation of factual knowledge. Students then use observation, imagination, and reasoning about scientific phenomena they are studying to organize knowledge within a conceptual framework. The teacher monitors the changing concepts