80% of the [students completing introductory college physics courses] could state Newton's Third Law at the beginning of the course. FCI data showed that less than 15% of them fully understood it at the end". These results have been replicated in a number of studies involving students at a range of institutions (see sources section below). That said, there remain questions as what exactly the FCI measures. Results using the FCI have led to greater recognition in the science education community of the importance of students' "interactive engagement" with the materials to be mastered. Since the development of the FCI, other physics instruments have been developed. These include the Force and Motion Conceptual Evaluation concept and the Brief Electricity and Magnetism Assessment. For a discussion of how a number of concept inventories were developed see Beichner. In addition to physics, concept inventories have been developed in statistics, chemistry, astronomy, basic biology, natural selection, genetics, engineering, geoscience. and computer science. In many areas, foundational scientific concepts transcend disciplinary boundaries. An example of an inventory that assesses knowledge of such concepts is an instrument developed by Odom and Barrow (1995) to evaluate understanding of diffusion and osmosis. In addition, there are non-multiple choice conceptual instruments, such as the essay-based approach and the essay and oral exams concept to measure student understanding of Lewis structures in chemistry. Caveats associated with concept inventory use Some concept inventories are problematic. The concepts tested may not be fundamental or important in a particular discipline, the concepts involved may not be explicitly taught in a class or curriculum, or answering a question correctly may require only a superficial understanding of a topic. It is therefore possible to either over-estimate or under-estimate student content mastery. While concept inventories designed to identify trends in student thinking may not be useful in monitoring learning gains as a result of pedagogical interventions, disciplinary mastery may not be the variable measured by a particular instrument. Users should be careful to ensure that concept inventories are actually testing conceptual understanding, rather than test-taking ability, language skills, or other abilities that can influence test performance. The use of multiple-choice exams as concept inventories is not without controversy. The very structure of multiple-choice type concept inventories raises questions involving the extent to which complex, and often nuanced situations and ideas must be simplified or clarified to produce unambiguous responses. For example, a multiple-choice exam designed