Another line of research, active to the present day, has concerns close to those of the work
described in this article. In the early 1980s, a number of studies appeared that seemed to indicate
substantial problems with standard physics instruction. Although students could solve many of the
problems that are typical of introductory instruction, they apparently could not answer some very
basic qualitative questions. For example, Halloun and Hestenes, in a study that employed a
multiple-choice test given to hundreds of university physics students, found that 44% of these
students exhibited the belief that a force is required to maintain motion (Halloun & Hestenes,
1985b).