Randy BellÕs ÒCandleÓ
observations, inferences and NOS
Presenter: Katey
Shirey, Washington-Lee High School, katherineshirey@gmail.com
Va. SOL:
PH.3 The
student will investigate and understand how to demonstrate scientific reasoning
and logic. Key concepts include:
c)
evaluation of evidence for scientific theories;
d)
examination of how new discoveries result in modification of existing theories
or
establishment
of new paradigms; and
e)
construction and defense of a scientific viewpoint (the nature of science).
National Standards:
Science as Inquiry Standard. p. 105
In the vision presented by the Standards,
inquiry is a step beyond ''science as a process," in which students learn
skills, such as observation, inference, and experimentation.
Topic/Concept
In this demo the teacher uses a seemingly innocent
ÒcandleÓ to practice observation and inference, then delivers a discrepant
event to cause students to re-examine their theories about the situation. This demo also is a great example for
the Nature of Science, that here are more than one possible explanation for
observations, science in tentative and theories can change as new evidence is
gathered.
Materials
á string cheese
á almond sliver
á skinny coffee stirrer type straw
á lighter
Safety Considerations
You could burn yourself with fire slightly, but no
worse than a piping hot pizza could.
Presentation
Set
up the candle before hand. To set
up, insert straw/stirrer into the ÒcandleÓ the long way to reduce itÕs
jiggling. Put one almond sliver in
one end to resemble a wick. You
might want to model each of these additionally with an exacto knife for
realism. Burn the almond sliver
and blow it out so it looks like it has burned before, and so that it lights
easier the second time.
In
front of the class, dim the lights (or not) and tell the students youÕd like
them to make observations about a very special piece of equipment. Present the ÒcandleÓ but donÕt call it
by name. Have students observe on
paper or out loud. Light the
candle and ask them to continue observing. After about 20 seconds it might start to sputter so youÕll
have to cut the observing short.
Tell
them that youÕre going to do something and they should continue taking
observations. Bite the top off the
candle, lit almond and all, chew and swallow. Ask them to continue making observations.
Discussion,
were some of their observations really inferences? Were any of them not surprised?
How the physics is demonstrated
This is a NOS activity. It does give an opportunity to observe and infer, but it mostly is about assumptions and how dangerous they are in science. It is also about how new evidence changes our current understandings.
Sources & References