Teacher instructions

Work through this resource material in the following sequence:

10 minutes

Tune in: The fire triangle model

10 minutes

Find out: The three requirements for fire

30 minutes

Take action: Is the model accurate?

10 minutes

Reflection

Please make sure to read the About Cool Burning Fact Sheet.

Tune In: The fire triangle model

Step 1

Show students the edited image below (also available here: Fire Triangle Image - no labels):

Explain: The fire triangle model of understanding fire is used to explain the three requirements to start and sustain a fire.

Discuss: What do you think the three requirements might be?

Find Out: The three requirements for fire

Step 1.

Watch:

The problems of hot burns - (https://vimeo.com/79474010)

Step 2.

Discuss:

What are some differences between cool and hot fires?
What are some problems with hot fires?
Do people benefit from the use of fire?
What are some safety issues surrounding the use of fire?

Step 3.

Explain:

Cool burns are a land management technique. Started soon after the wet season, before the grass completely dries out, cool burns do not damage plants, seeds or animals to any significant extent. During a cool burn, the grasses on the ground burn slowly, allowing most of the small animals to escape. Seedlings, green grass, tree trunks and fallen logs are not burnt or damaged. The rising heat from the burning grass usually won’t singe the eucalyptus leaves above. Overnight, the cool moisture in the air will put out any remaining fires before the morning. Hot burns are those that we associate with bushfires like the ones experienced in the recent Black Summer fire season (2019/20). In these circumstances, the fire burns at a high temperature, seriously damaging or even destroying vegetation, and burning out of control for many days or even weeks. The practice of cool burning has been used by Aboriginal and Torres Strait Islander peoples for many thousands of years. However, in recent years, scientists from around the world have become more and more interested in these practices as one way of managing devastating bushfires.

Step 4.

Explain:

The fire triangle model of understanding fire explains the three requirements to start and sustain a fire. These three things are:

A source of heat is required to start and sustain a fire
A source of fuel is needed to burn
An adequate supply of oxygen is needed for a burning/chemical reaction.

Image also available here: Fire Triangle Image.

More information about fire can be found on the Fire Factsheet.

Step 5.

A candle can be used to demonstrate the fire triangle.

Discuss: When a candle is burnt:

What is the fuel?
Where does the heat come from?
Where does the oxygen come from?

Step 6.

Discuss:

The fire triangle is used by firefighters in countries like Australia and the USA to explain how fires work. They say if one of these three elements is not present then there can’t be a fire. Do you think this is true? How can we test this?|

Take Action: Is the model accurate?

Depending on your school's facilities for students to conduct safe experiments, decide whether the experiments will be done by small groups or as a teacher demonstration. Before conducting any experiments or demonstrations, ensure students understand your Lab Safety Rules.

Activity 1 - Designing the experiments

Students need to design three experiments that explain the roles of fuel, heat and oxygen. These will be:

An experiment that removes the fuel from a fire
An experiment that removes the heat from a fire
An experiment that removes the oxygen from a fire.

Students can work in small groups or pairs to design their experiments.

Their experiment write-up (available on the Student Worksheet) should include:

Aim - the aim of the experiment, expressed in a single sentence.
Method - a written description of what they will do in their experiment. They should explain the experiment step by step. Their experiment needs to show the distinct roles of heat, oxygen and fuel.
Predictions - a written description of their predictions as to the experiment's results.
Safety considerations - a written explanation of how they will remain safe during the experiment. Questions are available on the Student Worksheet to help students design their experiments. Students must submit their designs for teacher feedback before they are allowed to do the experiments.

Activity 2 - Recording observations

Students complete their experiments and record their observations. They compare their observations with their predictions.

Reflection

As a class, share your results.

Teacher reflection

Take this opportunity to reflect on your own teaching:

• What did you learn about your teaching?
• What worked well?
• What didn't work well?
• What would you share?
• Where to next?
• How are you going to get there?

Investigating the Fire Triangle Model

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