transactional distances. Some of these are listed below together with a brief description. Zhang’s Scale of Transactional Distance (2003): By the turn of the millennium, distance education had evolved from being synonymous with correspondence courses to being largely web-based. Aixu (Monica) Zhang built on Michael G. Moore's theory by proposing that transactional distance could be viewed as a measure of the student's difficulty in becoming actively engaged with their online learning environment. She defined transactional distance by four sets of variables (the Transactional Distance between Students and Students (TDSS), the Transactional Distance between Students and the Teacher (TDST), the Transactional Distance between the Student and the Content (TDSC), and the Transactional Distance between the Student and the Instructional Technology (TDSI). She found that these four sets of variables were highly and statistically correlated with Student Satisfaction, which she adopted as her surrogate measure for Transactional Distance. Her work lead to a 31 element statistically reliable and significant Scale of Transactional Distance. Relative Proximity Theory (Swart et al., 2013): Zhang's Scale of Transactional Distance provides a numerical measure for transactional distance based on a five-point Likert Scale. Such a measure assumes meaning only when compared to another similar measure such as, for example, in a statistical pre –post intervention comparison. Many studies do not lend themselves to pre-post intervention comparisons. Relative Proximity Theory borrows from gap, or needs analysis (Kaufman & Guerra, 2013) to yield the transactional distance between an actual and desired state. For example, the transactional distance between an actual class and an ideal class. Revised Scale of Transactional Distance (Paul et al., 2015): There are many changes in the educational environment that have occurred since Zhang developed her Scale of Transactional Distance: Online education is the fastest growing segment of higher education, mobile computing has become ubiquitous, MOOC's provide an unprecedented amount of online content to learners and instructors alike. Zhang's model was re-evaluated in light of these changes. The results provided a 12 element parsimonious version of Zhang's scale which has excellent factorial validity and reliability, yields better fit statistics, and is easier and less time consuming to apply than the original scale. Coll-TD Scale (Wengrowicz et al., 2014): This scale builds on Michael G. Moore's Theory of Transactional Distance to measure the transactional distances of students who are conducting research in virtual group collaborative environments. It defines Transactional Distance as composed of six sets of variables