Blended learning is an approach to education that combines online educational materials and opportunities for interaction online with traditional place-based classroom methods. It requires the physical presence of both teacher and student, with some elements of student control over time, place, path, or pace. While students still attend 'brick-and-mortar' schools with a teacher present, face-to-face classroom practices are combined with computer-mediated activities regarding content and delivery. Blended learning is also used in professional development and training settings. Blended learning is an approach to education that combines online educational materials and opportunities for interaction online with traditional place-based classroom methods. It requires the physical presence of both teacher and student, with some elements of student control over time, place, path, or pace. While students still attend 'brick-and-mortar' schools with a teacher present, face-to-face classroom practices are combined with computer-mediated activities regarding content and delivery. Blended learning is also used in professional development and training settings. Blended learning is highly context-dependent therefore a universal conception of it is hard to come by. Some reports have claimed that a lack of consensus on a hard definition of blended learning had led to difficulties in research on its effectiveness. However, a 2015 meta-analysis that historically looked back at a comprehensive review of evidence-based research studies around blended learning, found commonalities in defining that blended learning was 'considered a combination of traditional f2f modes of instruction with online modes of learning, drawing on technology-mediated instruction, where all participants in the learning process are separated by distance some of the time.' This report also found that all of these evidence-based studies concluded that student achievement was higher in blended learning experiences when compared to either fully online or fully face-to-face learning experiences. 'Blended learning' is sometimes used in the same breath as 'personalized learning' and differentiated instruction. The terms 'blended learning', 'hybrid learning', 'technology-mediated instruction', 'web-enhanced instruction', and 'mixed-mode instruction' are often used interchangeably in research literature. Although the concepts behind blended learning first developed in the 1960s, the formal terminology to describe it did not take its current form until the late 1990s. One of the earliest uses of the term appears in a 1999 press release, in which the Interactive Learning Centers, an Atlanta-based education business, announced a change of name to EPIC Learning. The release mentions that 'The Company currently operates 220 on-line courses, but will begin offering its Internet courseware using the company's Blended Learning methodology.'The term 'blended learning' was initially vague, encompassing a wide variety of technologies and pedagogical methods in varying combinations (some making no use of technology whatsoever). In 2006, the term became more concrete with the publication of the first Handbook of Blended Learning by Bonk and Graham. Graham challenged the breadth and ambiguity of the term's definition, and defined 'blended learning systems' as learning systems that 'combine face-to-face instruction with computer mediated instruction'. In a report titled 'Defining Blended Learning', researcher Norm Friesen suggests that, in its current form, blended learning 'designates the range of possibilities presented by combining Internet and digital media with established classroom forms that require the physical co‐presence of teacher and students'. Technology-based training emerged as an alternative to instructor-led training in the 1960s on mainframes and mini-computers. The major advantage that blended learning offers is scale, whereas one instructor can only teach so many people. One example is PLATO (Programmed Logic for Automatic Teaching Operations), a system developed by the University of Illinois and Control Data. PLATO in particular had a long history of innovations and offered coursework from elementary to the college level. Mainframe-based training had a number of interface limitations that gave way to satellite-based live video in the 1970s. The advantage here was serving people who were not as computer literate. The major challenge was the expense required to make this work. In the early 1990s, CD-ROMs emerged as a dominant form of providing technology-based learning as bandwidth through 56k modems weren't able to support very high quality sound and video. The limitation to CD-ROMs was tracking completion of coursework, so learning management systems emerged as a way to facilitate progress tracking. The aviation industry used this heavily to track how well one did on courses, how much time was spent, and where someone left off. AICC, Aviation Industry Computer-Based Training Committee, was formed in 1988 and companies such as Boeing used CD-ROMs to provide training for personnel. Modern blended learning is delivered online, although CD-ROMs could feasibly still be used if a learning management system meets an institution's standards. Some examples of channels through which online blending learning can be delivered include webcasting (synchronous and asynchronous) and online video (live and recorded). Solutions such as Khan Academy have been used in classrooms to serve as platforms for blended learning. There is little consensus on the definition of blended learning. Some academic studies have suggested it is a redundant term. However, there are distinct blended learning models suggested by some researchers and educational think-tanks. These models include: It is important to note that even blended learning models can be blended together and many implementations use some, many, or even all of these as dimensions of larger blended learning strategy. These models, for the most part, are not mutually exclusive. There are many components that can comprise a blended learning model, including 'instructor-delivered content, e-learning, webinars, conference calls, live or online sessions with instructors, and other media and events, for example, Facebook, e-mail, chat rooms, blogs, podcasting, Twitter, YouTube, Skype and web boards'. Blended instruction is reportedly more effective than purely face-to-face or purely online classes. Blended learning methods can also result in high levels of student achievement more effective than face-to-face learning. By using a combination of digital instruction and one-on-one face time, students can work on their own with new concepts which frees teachers up to circulate and support individual students who may need individualized attention. 'Rather than playing to the lowest common denominator – as they would in a traditional classroom – teachers can now streamline their instruction to help all students reach their full potential.' Proponents of blended learning argue that incorporating the 'asynchronous Internet communication technology' into higher education courses serves to 'facilitate a simultaneous independent and collaborative learning experience'. This incorporation is a major contributor to student satisfaction and success in such courses. The use of information and communication technologies have been found to improve student attitudes towards learning. By incorporating information technology into class projects, communication between lecturers and part-time students has improved, and students were able to better evaluate their understanding of course material via the use of 'computer-based qualitative and quantitative assessment modules'.