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1. Fire

From the beginning, fire was considered a powerful and terrifying element because it was associated with threatening natural events: volcanoes and storms, for example. The “taming” of fire changed the course of human history, allowing people to cook food before eating it, which meant a far more varied and healthy diet. In the 18th century, Lavoisier discovered that fire was a chemical phenomenon, what we call combustion. In the case of fire, the basic effects of combustion are light and heat.
For a fire to start, there must be fuel, (such as wood or coal), oxygen (which is in air) and a high enough temperature.

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Observing. To observe means to look purposefully, to notice, to make note. To be a good observer you need concentration, patience and an ability to catch details.

The easiest and safest way of observing fire in the classroom is to light a candle. The object of our observation will be the flame. In doing so we should concentrate on certain aspects, looking at them in question form:

1.	About how tall is the flame?
2.	Is the colour of the flame uniform?
3.	Does the flame flicker? When and how does it flicker?
4.	When it flickers, does it produce smoke?
5.	When does it produce more smoke: when it flickers a little or when it flickers a lot?
6.	Does the flame move if there is no air current?
7.	Does it move more when there is an air current or when there is not?
8.	How would you describe the shape of the flame?
9.	How would you describe the type of light that it emits? (intense, weak, bright, etc.)
10.	Does it give off heat? Would it burn you if you got too close?