OVERHEAD PROJECTOR
TIMELINE OF PROJECTORS
LATE 1800S: THE MAGIC LANTERN
Magic lanterns projected images printed on glass slides. Oil lamps and candles served as light sources for the magic lantern.
1925: THE FILMSTRIP PROJECTOR
Filmstrips were used to show educational films in classrooms, serving as a predecessor of videocassettes, DVDs and Blu-ray technology. Filmstrip projectors allowed teachers to pause presentations for class discussions by turning a knob, and the projectors were widely used in classrooms until VCRs replaced them in the 1980s.
1960S: THE OVERHEAD PROJECTOR
Roger Appeldorn created a machine that projected the image of writing on clear film in the early 1960s. The U.S. Army used a version of the overhead projector for training purposes during World War II. Overhead projectors such as the Tel-E-Score, were also used in bowling alleys to project scores. Appeldorn specifically reached out to educators to promote the product and it wasn’t long before it became a mainstay in classrooms through the 1970s, 80s and 90s.
1980S: THE DATA PROJECTOR
A data projector takes signals from a video source, such as a computer or television, and projects an image on a projection screen. Early data projectors used a single cathode ray tube (CRT) to project a monochrome image. CRT projection systems have since given way to lighter and more convenient projection technologies, such as liquid crystal display panels (LCD) and digital light processing (DLP).
2010: THE 3D PROJECTOR
Implementing 3D technology in schools became more affordable in 2010, when manufacturers included DLP chips in their projectors. Projectors marked “3D Ready” can produce two virtually simultaneous images. Then, with the use of 3D glasses images are then streamed to the wearer’s eyes.
Since the late 1800s, educators have been using overhead projectors to integrate technology into their classrooms. Modern day projectors have evolved significantly in technology, weight and size since they were first introduced. However, today’s projectors continue to serve the same basic purpose, which is to transfer images onto a surface. Overhead projectors were initially used in bowling alleys and the Tel-E-Score was used to project written bowling scores on screens. The U.S. Army also used a version of the overhead projector for training purposes during World War II.
The eventual educational use of the overhead projector was brought about by the need for greater classroom efficiency. This also led to improvements in the production of overhead projectors such that they became sturdier and less expensive. The overhead projector became increasingly popular as educators found that it could meet the pedagogical needs of students and improve classroom management, as this new technology allowed teachers to remain facing students while writing down important information for students to either read and or copy.
Although the overhead projector was a popular instructional tool in the classroom, not everyone believed that students’ learning experiences were improved by using this technology. According to Knowlton (1992) the use of a projector enables teachers to move much more quickly through the material, but consequently avoiding students and their questions by cutting out distractions and anything that may slow down the information and learning progress.
The overhead projector may never have come to exist in classrooms had it not been for the emphasis on visuals in education, combined with the development of this instructional technology during World War II. The overhead projector has impacted and influenced the way educators prepare for and present materials in class, as well as the way in which students experience learning in the classroom.