Historical information
The first electric holiday tree lights were made in 1882
by Edward Johnson, an employee of Thomas Edison.
Johnson wanted a safer way than candles to decorate
his tree. The idea was slow to catch on and it was not
until after 1895 when President Cleveland had electric lights on the White House family tree that holiday lights became popular with the public. The first
lights were extremely expensive and only the wealthy
could afford them. Around 1950, the miniature lights
that were the precursors to our modern lights were
introduced in Italy (Nelson 2008). These lights were
small and connected in series so that they were cooler
and less expensive to operate than the larger parallel wired lights popular at that time. While series holiday lights were popular prior to the 1950s, they were
larger and there were fewer lights on a string—often
eight. Today, most miniature lights contain two 50-
bulb strings parallel with one another to make the
common 100-bulb sets.
The first twinkling lamps were the larger parallel
types, and each bulb flashed on and off individually.
The most common inexpensive blinking lights in use
today are the miniature variety in series, in which one
bulb blinks, causing the remaining bulbs to flash on and
off. The newest blinking lights make use of electronics
that can be programmed to create numerous intricate
designs and flashing patterns.
The above short history of holiday lights demon-
strates a key idea in engineering—that engineering is
more than simply the invention of an idea, but also the
idea’s evolution through innovation: “Invention is the
process of turning ideas and imagination into devices
and systems. Innovation is the process of modifying an
existing product or system to improve it” (ITEA 2002,
p. 110). After the initial invention of holiday lights on a
string, many people developed innovations to improve
upon them.
In this article, like in all Everyday Engineering columns, we will integrate ITEA standards (like the one
above) for grades 6–8 with appropriate science content.
We will present a 5E inquiry lesson: Making a switch
from a bimetallic strip to create a blinking bulb. (For
more information on the 5E inquiry model see Moyer,
Hackett, and Everett 2007).