From the Sourcebook for Teaching Science
Michael Faraday (1791-1867) was a British scientist who
invented the first electric motor and dynamo, demonstrated the relationship
between electricity and chemical bonding, and discovered the effect of
magnetism on light.
Faraday was not only
a brilliant scientist, but also a well-known educator who brought science to
the public through lectures he delivered each Christmas season at the Royal
Society in London[i]
Faraday’s Christmas Lectures were popular
because he illustrated concepts with numerous hands-on activities and
Faraday knew the importance
of observation in science and began his most famous lecture series by asking
to record as many
observations as possible about a burning candle.
Years later, science teachers continue to use
Faraday’s activity to encourage the development of observation skills.
Douglas Osheroff, the 1997 Nobel prize winner
in physics (for discovery of the superfluid phases of 3
reflected on the importance of
this activity in his own intellectual
“I remember quite well one
class assignment: to record our own observations of a burning candle.
I knew pretty well how a candle worked, and
simply wrote down an explanation of how radiant heat from the flame melted the
wax, which was then drawn up into the wick by capillary action, etc.
Mr. Hock read my explanation, and then came
to me and pointed out that what I had written could not possibly have been
drawn from my own observations.”[ii]
Osheroff had not made observations as
requested, but had relied on his prior knowledge to explain what he was
Mr. Hock’s comments helped
Osheroff distinguish observation from inference, and this distinction
ultimately helped him in his career as a scientist.
– Observations of a Candle
- Record all observations on the class data sheet. Place your initials in parentheses following each set of observations.
Materials: small candle, matches, tongs, beaker,
funnel, clay or putty, bromthymol blue or phenol red indicator, test tube
clamp, safety glasses, dull butter knife, lamp oil (optional).
The purpose of this
activity is to record as many observations of a candle as possible. Refer to
table 5.2 for ideas on the types of observations that may be made. Record your observations in a laboratory
notebook or worksheet. Firmly plant a
candle in a small clump of clay. Using
beaker tongs, suspend a clean, cool beaker over the unlit candle as illustrated
(figure 5.6A) and record your observations.
Repeat the procedure with a funnel on which there are drops of the pH
indicator methylene blue or phenol red.
Does the indicator change color?
Put on safety goggles and
light the candle and record all observations (figure 5.6C, table 5.2). Using beaker tongs, suspend a cooled beaker
over the flame as shown in figure 5.6D.
What observations can you make about the inside of the beaker? Repeat the procedure with a funnel in which
there are drops of bromthymol blue (figure 5.6E).
Place a dry, clean beaker
over the flame (figure 5.6F) and make
observations as the flame is extinguished.
Repeat the procedure with different sizes of glass beakers. Is there any correlation between the size of
the glass beaker and the time it takes to extinguish the flame? Remove the beaker, and re-light the candle by
placing a match in the smoke near the wick (figure 5.6G). Is it possible to re-light the candle simply
by moving the flame into the smoke?
Using a dull knife, cut the wick free from the candle and
place one end of the wick in a dish of water. Light the other end of the wick
(figure 5.6H). What do you observe? Dry
the wick off and place it in a dish of lamp oil and re-light it. What do you observe?
Activity 5.2.2 –
Developing questions about the candle.
In his introduction to the classic candle activity, Michael
Faraday wrote: “We come here to be philosophers; and I hope you will always
remember that whenever results happen, especially if it be new, you should say,
'What is the cause? Why does it occur?' and you in the course of time will find
out the answer.” Write down as many
questions as you can based upon the observations you made in activity
5.2.1. For example, “What is wax? What is the wick? Why is the wax soft? Why does the wick turn black? Why does the wax melt? Why does the smoke ignite? What is the substance that appears on the
glass above the flame? Why does the
indicator turn color when placed over the candle? Do all candles burn the same?...”
- Write you own scientifically-oriented questions and submit them in the data table
Faraday, Michael. (1963). Chemical
History of a Candle. New York: Viking Press.
Osheroff, Douglas. (1997). "Puttering Around in the Basement on the Road
to Stockholm", Keynote Address for the California State Science Fair. May
Photographs of Pasteur, Eijkman and Edison are in the