Randy Bell’s “Candle” 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.



In this demo the teacher uses a seemingly innocent “candle” 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.



Š      string cheese

Š      almond sliver

Š      skinny coffee stirrer type straw

Š      lighter


Safety Considerations

            You could burn yourself with fire slightly, but no worse than a piping hot pizza could.



            Set up the candle before hand.  To set up, insert straw/stirrer into the “candle” the long way to reduce it’s 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 you’d like them to make observations about a very special piece of equipment.  Present the “candle” but don’t 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 you’ll have to cut the observing short.

            Tell them that you’re 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

Please see Teaching the Nature of Science Through Process Skills: Activities for Grades 3-8  By Randy L. Bell  ISBN-13: 9780205433339