The Overhead Projector

Visuality and Materiality

Authored by: Josh Zimmerman , Ken S. McAllister , Judd Ethan Ruggill

The Routledge Companion to Media Technology and Obsolescence

Print publication date:  December  2018
Online publication date:  November  2018

Print ISBN: 9781138216266
eBook ISBN: 9781315442686
Adobe ISBN:

10.4324/9781315442686-7

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Abstract

Do you remember this? The teacher flicks a switch and the room darkens. Another switch clicks and the classroom’s overhead projector hums to life (its whining cooling fan clearly in need of a new bearing) and casts a 5-foot slightly-keystoned square of light onto the wall. The retractable projection screen hanging from the ceiling near the front of the classroom—just above the chalkboard and behind the sanitized roll-up anatomy chart—has been broken for months, so the wall is its imperfect replacement. After struggling to separate a stack of cellulose acetate sheets (a.k.a. transparencies) and keep them from slipping onto the floor, the teacher places the first one on the projector’s glass surface, adjusts the ostrich-like focal lens, and suddenly the crudely drawn image of a cell’s membrane and cytoplasm covers the wall, shaded here and there by stray chalk marks, eraser dust, and pieces of cellophane tape that are brown at the edges. For the next 30 minutes, the teacher uses a felt-tipped pen to draw various additional cell structures on the projected diagram, explaining the development and function of each in turn. When the bell rings at the end of class, the students disgorge into the hallway while the teacher turns the lights back on and switches off the projector, stowing its cord. Between classes, the instructor uses an old wet rag to wipe the marker off the acetate sheets, preparing them for the next session. This was standard operating procedure in high school Biology classes until well into the new millennium.

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