While observing a “candle” the importance of making good observations in science are discussed. The conversation shifts to making inferences when the teacher blows out the “candle” and eats it.

Note: this activity is meant as a demonstration only

observations, inferences

Materials (for instructor only)
  • Apple corer
  • Large apple
  • Nut (almond, walnut)
  • Paring knife
  • Matches
  • Optional: Fruit Fresh
  • Optional: bubble gum and small aluminum pie plate

Figure 4: Supplies to help create an edible candle.
Getting Ready
Prior to meeting with your class it will be necessary create the “candle”. Use an apple corer to create the cylindrical part (the base) of the candle by pushing it through the largest off-center portion of an apple. It is important to not use the core (seeds taste yucky) and optionally you may want to put Fruit Fresh on the outside of the apple of it to prevent browning. To minimize browning the cored apple cylinder should not be created too far in advance of the activity. Use the paring knife to remove any peel and also create small slice in the top of the base which will serve as an entrance for the wick. To create the wick cut a thin sliver of the nut about 2 cm long. Push the wick into the top of the candle where the knife cut a slot. Light the wick momentarily – this will blacken it to make the wick appear more realistic.

An optional candle holder can be created with the help of bubble gum and a small aluminum pie plate. Chew the bubble gum and place it the center of a clean, unused aluminum pie plate. Gently press the base of the candle into the bubble gum and it should stand up straight. The point of using bubble gum as an adhesive is to ensure the candle is still safe to eat when pulled from the holder.

It is recommended that a few wicks are lit and allowed to burn completely in order to know how long the candle lasts.

1. Start class by discussing the importance of observations in science. Perhaps go over the definition of observations and review what our senses are. Additionally, qualitative and quantitative observations can also be discussed.
2. Tell the class that today they will be making careful observations of a candle and they should do their best to describe what they observe.
3. Light the “candle” and compile a list of observations from the students. You may wish to discuss if the observations tend to be more qualitative than quantitative.
4. Blow out the candle and eat it.
5. Have students make inferences about what they just observed. Additionally, students can revise earlier observations based upon them witnessing the candle being eaten.

Observations can be defined as data gathered using our senses. The most common sense used for observation is sight; however, the other senses can be helpful when investigating a natural phenomenon. Except in special circumstances taste is generally not used in the science lab. Observations can be divided into quantitative and qualitative, with quantitative observations involving measurement and numbers while qualitative observations do not. An inference is a reasonable explanation that attempts to explain an observation. An observation is a fact (or is meant to be) while inference is a guess that attempts to explain a fact (or what is believed to be factual). Inferences can change as more observations are made.

A nut contains stored chemical energy that can be released during combustion (when it is lit on fire). They contain large amounts of both saturated and unsaturated fats. Burning peanuts is a reaction with oxygen (combustion) that releases the energy contained in the bonds of these fats in addition to the energy released from burning proteins and carbohydrates.

Figure 5: an edible candle - bubble gum adhesive at the bottom/apple core/almond sliver

*This activity was adapted from one created by John P. Williams, Associate Professor of Chemistry, Miami University Hamilton

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