Lesson Plans > Module 1 > Lesson 1 Part A:

Part A Observation and Inference: Using Inquiry Activity “The Burning Candle”

Prep time: 10 minutes Class time: 20 minutes


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 is also a great example for the Nature of Science, that there is more than one possible explanation for observations, that science is tentative, and that theories can change as new evidence is gathered.

Learning Goals

The student will be able to:

  1. Understand that scientific knowledge is based on observation and inference.
  2. Understand that an OBSERVATION is recognizing and noting a fact to gather information about the world using our five senses, and an INFERENCE is a possible explanation or guess about an observation.


If your students are like mine, this straightforward concept will likely be difficult for them to understand and accept. Most students hold the oversimplified view that scientific knowledge is solely based upon the accumulation of careful observations. For them, the mantra of the scientist is much like that of Sergeant Joe Friday on the old television show Dragnet: “Just the facts, Ma’am.” In this view, the reliance on careful observation coupled with the avoidance of subjective thought and speculation distinguishes science from other disciplines. In actuality, the practice of science is much more complex (and interesting) than simply making careful observations.

– Excerpt from Randy Bell’s Book (2008),p.36


  • Begin with a discussion on the definition of observation. Have students define observation. Common responses include:
    • Looking at something
    • Using any of your five senses to collect information
    • Making measurements

    These comments are accurate and present a different perspective of the way the term observation is used in science. Remind students that observing in science can mean using any of your five senses.

  • Set up the candle beforehand. To set up, insert straw/stirrer into the “candle” the long way to reduce its jiggling. Put one almond sliver in one end to resemble a wick. You might want to model each of these additionally with an X-Acto 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 unlit “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.
  • Teachable Moment: Tell them that you’re going to do something and they should continue taking observations.
  • Dramatically 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 actually inferences? Were any of them not surprised?
  • The goal of the segment is for the students to understand the meaning of inference. Acceptable definitions would be something like the following:
    • “To reach a conclusion based on evidence”
    • “Using observations to reach a logical conclusion”
    • “An observation is what you see, feel, hear, taste, or smell. An inference is what you think.”

Alternative Activity Procedures: Crazy Ketchup


Exit Ticket

  • Define observation.
  • Give examples of inference.
  • True or False: Scientific knowledge is based on observation and inference.

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