ACT/SAT Practice #1

In 1948, graduate students, Norman Woodland and Bernard Silver, took on a problem that had troubled retailers for years: how to keep track of store inventories. Inspired by the dots and dashes of Morse code, however, Woodland and Silver created a system of lines that could encode data. Called a symbology, the pattern created by the spacing and widths of the lines encodes information by representing different characters.

• NO CHANGE

• students, Norman Woodland and Bernard Silver

• students Norman Woodland and Bernard Silver

• students Norman Woodland and Bernard Silver,

Inspired by the dots and dashes of Morse code, however, Woodland and Silver created a system of lines that could encode data.

• NO CHANGE

• in other words,

• consequently,

• DELETE the underlined portion

The first bar code was composed of four white lines set at specific distances from each other on a black background. The first line was always present.

• NO CHANGE

• distances so that each was separated, one from the

• locations, each one set apart from the

• lengths of distance from each

Depending on the presence or absence of the remaining three lines, up to seven different arrangements were susceptible and, therefore, seven different encodings.

• NO CHANGE

• responsible

• possible

• capable

Today, twenty-nine white lines making more than half a billion encodings possible.

• NO CHANGE

• which make

• to make

• make

To create a barcode scanner, Woodland and Silver adapted technology from an optical movie sound system. Their prototype scanner used a 500-watt bulb, a photomultiplier tube (a device that detects light), and an oscilloscope (a device that translates electronic signals into readable information). Although successful, the concoction was both large and costly

• NO CHANGE

• contraption

• substance

• stuff

In today’s scanners, a laser sends light back and forth across a bar code. While the black lines absorb the light, the white lines reflect it back at a fixed mirror inside the scanner.

• NO CHANGE

• them

• ones

• one

For example, progress stalled until the 1970s, when laser technology (both more compact and less expensive) became available.

• NO CHANGE

• As a result,

• However,

• Even so,