An independent search on the history of Educational Technology revealed that this term is multi-faceted one. The field encompasses educational theory, design, processes, resources, implementation, hardware, software, evaluation, and management of education or training systems. Also the wide array of educational media and delivery technologies. For brevity, I chose a historical perspective of instructional media used in education specifically highlighting 1950 through to today.  Referencing the: The Ultimate History of Technology in Education I have highlighted some of these important developments.

Audio-visual aids of the 1950s introduced headphones and audiotaped lessons in schools.  BF Skinner a noted behaviorist introduced the Skinner teaching machine which rewarded students for correct responses. The photocopier was introduced by Xerox allowing the decentralized coping of teaching materials.

The 1960s saw microfilm technology introduced which enhanced access and research capabilities for students. Education TV was now available for home consumption, distance telelearning and use in class via a cable learning network.

In the 1970s the non-programmable handheld calculator was available in the classroom largely replacing the slide rule. Automatic marking machines debuted making the multiple choices exam a preferred assessment type.

The 1980s issued in the personal computer and CD ROM based educational programs. The lack of internet in schools limited computer usage to largely an enhanced typewriter replacement tool as word processing was the primary use.

In 1990 the internet became widely available but rudimentary connection speeds arrested efficient handling of large amounts of data. The lack of efficient Wi-Fi connections and portable devices precipitated hardwired computer labs for access in educational institutes.

The 21 first century it is all about access, interaction, and portability. Interactive smart boards increased content accessibility in the classroom, and the use of portable devices has increased engagement and participation. Portable smart devices now allow access from anyplace anytime. This enhanced access has enabled the development of the massive open online courses disrupting the traditional concepts in distance learning models. I believe the future trends in educational technology are in open content repositories and shard resource development.

Some further resources on the topic:

https://www.slideshare.net/fvsandoval/history-of-educational-technology

https://www.slideshare.net/PabloRuggiero/history-of-educational-technology-ppt?next_slideshow=1

http://institute-of-progressive-education-and-learning.org/a-history-of-education-technology/

http://faculty.weber.edu/eamsel/Research%20Groups/On-line%20Learning/Bonk%20(2006).pdf