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Lesson Plan

Meeting the Fire Triangle 2

Glacier National Park

Grade Level:

Upper Elementary: Third Grade through Fifth Grade

Subject:

Science

Lesson Duration:

60 Minutes

Common Core Standards:

3.SL.1, 4.SL.1, 5.SL.1

Essential Question

What are the three components of the Fire Triangle? What happens when one component of the Fire Triangle is removed?

Objective

Students will be able to construct a paper model of the Fire Triangle and explain how extinguishing a fire is analogous to removing one leg of a triangle.

Background

Fire can occur only if oxygen, fuel, and heat are available. These three components are called the “fire triangle.”

This activity is from the “Fireworks Education Program” curriculum, which can be found online. The traveling trunk that goes with this curriculum can be obtained from the Flathead National Forest Office in Kalispell or from the park in West Glacier. 

Preparation

• Be familiar with Meeting the Fire Triangle Lesson Plan 1
• Tree poster/picture
• Transparency of Fire Triangle
• Discussion questions

Procedure

Post or draw the Fire Triangle picture in the classroom. Ask students what is needed for a fire. Write  answers on the board. Then use the answers to discuss the three parts of the Fire Triangle: heat, fuel, and oxygen. The Fire Triangle transparency can be used as a transparency to guide discussion, but may not be necessary. 
At the end of the discussion, ask students to construct a paper model of the Fire Triangle Kit (student page 2); use this as an evaluative tool.

Discussion Points

1. What is fire? Fire is a rapid chemical reaction that combines fuel and oxygen to produce heat and light.  Carbohydrate + oxygen + heat g carbon dioxide + water vapor + heat + light C6H12O6 + 6 O2 + heat g 6 CO2 + 6 H2O + heat + light
2. Burnable things surround us every day. Why aren’t they on fire? An external source of heat is usually needed to start combustion. Once a fire has started, it produces the heat needed to continue burning. A fire can be put out if fuel, oxygen, or heat is removed. This idea is often depicted using a triangle (refer to the Fire Triangle poster). Remove any one of the three legs of a triangle, and it will collapse; remove any one of the required components of fire, and it will go out.
3. What is the fuel in fires we are familiar with? Most cars are fueled by gasoline, candles are fueled by melted wax, furnaces by natural gas or fuel oil, and campfires by wood.
4. What fuels a wildland fire? In nature, fire’s fuel is plant material. Use a tree picture to discuss nature’s fuels and illustrate these points: Tree crowns, high above the ground , provide some fuel; these include tree branches, leaves (needles are a kind of leaf), and trunks.  Fuels that lie on or right above the surface of the ground include dead and fallen needles,  eaves, grass, dead wood, stumps, and low shrubs. The main ground fuel is duff, the layer of dead, decaying plant material that makes up the top layer of soil. It contains decaying leaves, decaying wood, and roots. Sometimes it is mixed with mineral soil (very fine rock particles), which won’t burn.
5. Where does the oxygen for fire come from? Oxygen is plentiful in air. Students may be able to relate the “oxygen” part of the fire triangle to their fire-safety education: “Stop, drop, and roll” is one way to reduce the oxygen available to burning clothing. If a person runs with clothing on fire, the oxygen supply increases and the fire burns more intensely.
6. What heat sources do we use to start fires? Spark plugs in cars, pilot lights in appliances, and matches are some examples.
7. What provides heat for forest fires? In wildlands, nature provides heat in lightning and volcanoes. Matches, untended campfires, and cigarettes are the sources of heat for many  human-caused wildland fires. During the thousands of years when Native Americans were the only people living in North America, they often started fires to change the plant communities that provided their food and shelter. They used fire to make their campgrounds safe from fire and enemies, to improve grazing and berry supplies, and for many other reasons. After they obtained horses, Native Americans used fire to improve forage for their herds. Today, we would call these prescribed fires.
8. How does wind influence fire? Wind influences fire in many ways. Think about starting a campfire. If you blow on it, you provide extra oxygen and blow the heat toward the fuels, getting the fire to burn more intensely. If you blow too hard, especially across a small flame like a candle, you scatter the heat so much that the fire goes out. Wind helps forest fires spread by drying out fuels and carrying burning embers ahead of the fire.
9. Use the fire triangle to describe some ways to put out a fire. To slow down a fire or put it out, at least one of the three components of the fire triangle must be changed. Think about ways that both large and small fires are controlled. When all the wax is gone from a candle or all the fuel is burned in a campfire, it goes out. A fire line, used to control forest fires, is simply a path cut through all of a forest’s fuels—down to mineral soil. When the fire gets to the fire line, it runs out of fuel. When you throw water on a fire, you cut off oxygen and remove heat. You can also cut off oxygen by throwing dirt on a fire. Fire extinguishers and fire retardant dropped from airplanes remove heat and cut off oxygen from wildland fires.

Extension

Make a collage of familiar things that use combustion. Examples: Cars and gas appliances contain “burning chambers.” Electrical appliances may rely on combustion of coal to produce power. Barbecues, lanterns, and candles use fire. So do “real” fireworks displays. Use the components of the Fire Triangle to describe how combustion is controlled in these items.

Vocabulary

Fire Triangle, fuel, heat, hypothesis, model, oxygen, prescribed fire, tree crown.

Assessment Materials

Provide each student with a Fire Triangle Kit. Ask students to construct a Fire Triangle and label the parts correctly. Ask them to write a paragraph in which they do the following:

1. Describe a fire (candle, engine, campfire, and forest fire are all possibilities)

2. Tell one way to put it out

3. Explain what part of the Fire Triangle is removed when that method is used to put it out

4. Explain to students that this discussion has provided a model for how fires work. A model is like a hypothesis because it is an explanation for something observable, and it can be tested. 

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