Forest Series - Prescribed Fires - STEM Challenge
Fire Triangle Demonstration
Fire requires three elements to exist.
Oxygen: Just like people need oxygen to breathe, a fire needs oxygen to burn.
Heat: Without sufficient heat, a fire cannot start, nor can it continue to burn.
Fuel: Fuel is what feeds a fire, the same way that food keeps us going.
These three elements are commonly referred to as the "Fire Triangle." If the proper combination of each element is present, and a chemical reaction occurs, a fire can start.
Understanding the science of fire will help you understand how firefighters work to control or extinguish fire; and it can also help you to prevent fires from happening!
The Experiment
Materials:
a stopwatch
3 balls of clay or play-doh of different colours
3 birthday candles
a lighter or matches
a spray bottle full of water
a drinking glass or a glass jar
a baking sheet
a pencil and notebook for recording observations
1. Collect all the elements needed for the experiment.
2. Place the 3 balls of clay on the baking sheet. Place one birthday candle in the middle of each ball of clay. The candles should be just deep enough so they don’t risk falling. Each ball of clay will represent one of the fire triangle elements. You can add a ‘post it’ in front of each ball of clay to remind you which element it is.
3. To start, let’s test if fire really needs oxygen to burn! Which object from the materials list do you think we could use to test if the candle can burn without a source of oxygen?
4. With your teacher or parents' help, light the candle that is in the Oxygen clay ball. Place the glass or the jar over the candle. Start your stopwatch and wait for the flame to extinguish.
5. Repeat step 4 with a larger jar - what do you think will happen? What is the result?
How long did it take for the flame to go out? Write down the result on your recording sheet.
6. Next, we will test if fire truly needs heat to burn!
Which object from the materials list do you think we could use for this part, and how?
7. With your teacher’s help, light the candle that’s in the Heat clay ball. Start your stopwatch. Spray fine misting water above the candle flame until the flame goes out. How long did it take? Write down the result on your recording sheet.
8. Finally, we will test to see if fire really needs fuel to burn!
In this situation, what do you think is the candle’s fuel?
9. With your teacher’s help, light the candle that’s on the Fuel clay ball. Start your stopwatch. See if the candle burns out. Time how long it burns for.
Did the flame burn out? How long did it take? Why didn’t the clay become the fuel? Write down the results on your recording sheet.
Review your data
Did the flame go out every time?
Which element removal put out the flame the fastest?
Which element removal took the longest for the flame to go out?
Firefighters work with these elements to prevent and fight fires. Can you think of ways they remove fuel to prevent fires?
Are there ways they can remove heat to fight fires?
How would they remove oxygen to fight fires?
Have fun with this challenge! Stay safe!
What happens to a fire if any one of the 3 components of the fire triangle is reduced? Removed? What happens if more than one component is removed?
Answers
Firefighters work with these 3 elements to prevent and fight fires. Here are a few examples.
They remove fuel by creating handmade or machine made fire breaks or using prescribed fires to create a fire break.
They remove heat by dropping or spraying water on a fire.
Dropping big amounts of water on the fuels helps them remove oxygen too. They can also remove oxygen by using foam or fire retardant.
