The science of burning

The science of burning

Online interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about what is needed for burning to happen.

flames of fire

Imagine what our lives would be like without fire.
Fire brings us many benefits.
However, it is also very dangerous.
To make good decisions about managing fire we need to know a bit about the science of burning.

Question 1Change answer

What are the three things that are needed for a fire to burn?

1 2 3
the fire triangle
To check your answers, look at the fire triangle, which shows the three things needed for a fire to burn.  
If any are missing, burning will not take place.
Thinking about your answers
 

Fuel is the best answer.

Did you give an example of something, e.g., wood, coal, trees, natural gas, petrol, etc.?

Fuel is a better word to use because it covers all of these. Anything that will burn is a fuel. A fuel has stored energy that is released during burning mostly as heat and light.

Oxygen is the best answer.

Was air your answer?

Oxygen is a better answer. It is the particular gas in air that is needed for burning to continue. (This is a bit like our breathing. We breathe air, but it is the oxygen in the air that we need.)

Heat is the best answer.

Was your answer matches or a lighter?

Heat is a better answer because it covers anything that heats up the fuel enough to set it on fire. (It is the flame or spark from the match or lighter that ignites the fuel.)
The next four questions check how well you understand  the fire triangle in real life situations. 

Question

When making a hangi, wood is burnt in a pit in the ground to heat stones.
Which is the fuel for the fire?

    • Air

    • Stones

    • Wood

    • Dirt

Question

A  barbecue stops going when the gas in the gas bottle runs out.
Why does this happen?

    • There is no more oxygen.

    • There is no heat to set it alight.

    • There is no fuel.

Question

In very dry conditions, why is it dangerous to throw a  lighted cigarette butt out of a car window?

    • It provides a heat source.

    • It provides oxygen.

    • It provides fuel.

Question

If a pan of fat catches fire, one way to stop the fire is to put the lid on the pan. 

How does this stop the fat burning?

    • It removes the heat source.

    • It removes oxygen.

    • It removes fuel.

Task administration: 
This task is completed online and has some auto marking displayed to students, and some student self assessment.
Three resources about fire were developed together.
This resource, The science of burning, is designed to check students' knowledge of the components needed for burning to take place. We suggest you use this one first.
The other two, Fire: Keeping safe and Managing fire, require students to use their knowledge to support decision-making.
Copyright: 

flames of fire

(c): J.Fisher, PhotoKete.

All images copyright to PhotoKete can be freely used for educational purposes within New Zealand classrooms.


 

Level:
4
Curriculum info: 
Science, Knowledge, Material World
Keywords: 
changes, chemical change, combustion, burning, fire
Description of task: 
Task: Answer questions about the fire triangle. Assessment focus: elements necessary for combustion.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Use evidence
This resource provides opportunities to discuss how to make a decision from given information/evidence.
Science capabilities: 
Use evidence
Making Better Sense: 
Dissolving
Answers/responses: 
Question Response Y8 (11/2013)*
Name three things that are needed for a fire to burn.

Best answer

Fuel, oxygen, heat (any order)

Other acceptable answers

Examples of the above, e.g., wood, matches, air. (Refer to student feedback within task.)

All 3 correct - moderate

 

All 3 ( a mix of generic terms and specific examples, or all examples) - easy
When making a hangi, wood is burnt in a pit in the ground to heat stones. Which is the fuel for the fire? Wood moderate
A barbecue stops going when the gas in the gas bottle runs out. Why does this happen? There is no more fuel. very easy
In very dry conditions, why is it dangerous to throw a lighted cigarette butt out of a car window? It provides a heat source. easy
If a pan of fat catches fire, one way to stop the fire is to put the lid on the pan. How does this stop the fat burning? There is no more oxygen very easy

* Trialled on-line by 25 Year 8 students.

Diagnostic and formative information: 
The fire triangle
The most difficult element for the trial students to recognise was that a heat source (something to start the fire) is needed.
For fuel, wood was the commonest answer. One student mentioned coal.
For oxygen, 5 students named air.
 
Next Steps
Check that students understand that having a fuel and oxygen is not sufficient to start a fire. There is no fire until there is ignition. Get students to generate and compare lists of possible heat sources (e.g., a flame, lightning strike, spark from electricity, glowing heater bar,etc.)

Provide some examples of possible fuels, and discuss whether they are all equally easy to ignite. 

Fire in real life contexts 

The most difficult example for the trial students was identifying the fuel that heats the stones in a hangi. This may reflect the experiences of the trial students. Those who are familiar with hangi could be more likely to get this question correct.

Next Steps

Provide further examples within contexts that are familiar to your students, then move to exploring contexts that may be more surprising. Topical contexts that may interest students are bush fires, arcing of electricity lines in high winds, lightning strikes, oil tanker accidents, and flammable liquids.

A note about safety: Fire and children are not a good mix. Certain substances are banned in schools, e.g., never expose students to liquid fuels or other flammable liquids.

Make sure that safety guidelines are followed, and also check your school policies.

The Science Learning Hub includes Fire as a learning context 
 
Other ARB resources: