Burning Questions About a Candle: Teacher's Notes

Activity: Observations of a Burning Candle

Safety: First and Foremost

DISCLAIMER:
We offer this site as an educational tool. WE ARE NOT RESPONSIBLE FOR ANY INJURY OR DAMAGE CAUSED TO ANY PERSON, DIRECTLY OR INDIRECTLY, RELATING TO ANY OF THE DEMOS OR EXPERIMENTS LISTED AT THIS SITE. YOU ARE WHOLLY RESPONSIBLE FOR YOUR SAFETY.

Full Disclaimer

Objectives

National Science Education Standards: Content Standards

This activity fulfills the following within the Content Standards: 9-12

Materials

Method

Observations to make before you light the candle

Answer the following questions concisely. That is, use short sentences or sentence fragments, and only say what really needs to be recorded. You may want to work in pairs or small groups, each writing down observations, then periodically comparing notes and asking each other questions. If you do it this way, just remember: don't make critical comments! Be critical in your thinking, in the sense of always asking yourself "What does that mean anyway?" and not in the sense of "That's clearly wrong" or "What a dumb observation." Be positive in your approach, focus on the candle, and keep asking yourself questions in your own mind, especially questions that lead to further observations and more questions.

  1. Give a physical description of the candle and its components. What are the individual parts and what are they made of?
  2. How is the candle shaped? Why?
  3. At what angle do you plan to burn the candle? Why?

Do some physical "tests" on the candle using what you have on you or laying around the room. What do these tests tell you about its properties?

Do any of these tests give you an indication of the nature of the candle components at the molecular level? What do you know about the chemical nature and/or composition of these components?

Hypothesize what will happen when you light the candle and start it burning

Write down what you think will happen in terms of the observations you made above, especially with respect to the molecular level. Start a new page and be complete but concise.

Now, light the candle and watch what happens

In your notebook, record all the observations you can make regarding the lighting and burning of the candle. For this first set of observations, don't worry about asking questions so much as just making as many quick notes as you can. You should plan on spending a fair amount of time on this (more than a minute and less than an hour or two).

Hints:

It may take you a while to begin to think about what is happening. Be patient and work at the process. Once you begin to see how to ask questions related to what you are seeing, a snowball effect will occur that should open up whole new areas of observation for your critical consideration. Be sure to write down all of your thoughts and observations as they occur. Don't try to be critical of the material you write down, but simply put it down as quickly as possible. You will have plenty of opportunity later for evaluation and grouping of your data.

Take one observation that you recorded above and:

Now, pick another observation or two and carry out the same level of in-depth analysis. Try to relate the observations you made above to those that you make in this section.

You should find that as you practice this process of observation and recording your thoughts, you become better at asking questions about what is happening, and then writing down answers. This iteration is part of "doing science."

Repeat this process several times: this repetition is also part of doing science.

Now try to "watch" yourself observing and asking yourself questions:

Test Your Hypothesis by Doing an Experiment

After you feel like you have made enough observations to give you a pretty good understanding of what is actually happening during the burning process, it is time to do an experiment. An experiment results when you ask a question and then develop a method to answer that question. The experiment itself is actually the process of getting the answer.

So, here is what you need to do:

Be creative - you should be able to design experiments that you can do with what you can find in the lab or that you can easily acquire with very little effort. For example, holding a piece of glass over the candle as it burns (probably at an angle would work better) can help you answer questions about what is evolved or given off during the combustion process. Think of other simple ways of investigating further what is going on and see what kind of good experiments you can come up with.

Questions


Attached here is a printable form that has most of the questions and directions below, but with space for the students to write in their answers and observations while you work.

References

Also, check out these references that discuss classic candle experiments:

Other articles that might be of interest:


BACK HOME