Illuminations: On Fire

On Fire

Creating A Firewise Defensible Space

Students will learn about creating defensible space around a home using a series of fire protection zones. Students will then draw the zones that surround a house and estimate the area of each zone.

Learning Objectives
 
By the end of this lesson, students will be able to:
  • Model size in terms of their environment.
  • Describe the shape of zones and define the zone concept for firewise landscaping.
  • Estimate the area of an irregular shape.

Materials
 
In The Zone Activity Sheet
Protractors

Instructional Plan
Remind students of the question that they are trying to answer by the end of this unit:
If you live in an area where wildfires occur, what can you do to protect your family and property? That is, how can you reduce the probability of the fire spreading to your home?

Explain that one of the ways to protect a home is to create a defensible space around the home. To explain the ideas regarding defensible space, you can prepare a short introduction using the ideas from the list of Frequently Asked Questions about defensible space that occurs as the last page of the In The Zone activity sheet. Alternatively, you can simply have students read this list of questions and answers on this sheet as part of the lesson.

In The Zone Activity Sheet In The Zone Activity Sheet

Kids can also learn about defensible space zones from various web sites, if access to a computer is available:

To focus attention on the multiple variables that should be part of landscape design decision-making, engage the class in discussing the following questions:

  • Why do people landscape when they build homes?
  • In what ways is mathematics used in landscaping?
  • What factors should be considered when designing the landscaping for a home in a wildfire hazard area? How do these change for a home not in a wildfire area?
  • What is the relationship between proportion and landscaping?

Once students have an understanding of defensible space, allow them to work in pairs on the In The Zone activity sheet. Circulate as students work, and note the strategies that students employ to estimate the area of the zones. As necessary, offer assistance.

When students have completed the activity sheet, engage them in a discussion about what they discovered. In particular, ask the following questions to check their understanding of proportion and area:

  • What is the proportional relationship among the area of the zones, based on a visual estimate?
  • What strategies did you use to estimate the area within each zone?
  • The house can be divided into two rectangles, and the area of each could be determined. How would knowing the area of the house help when estimating the area of each zone?
  • How did your visual estimates compare to the actual measurements of the zones?

The In The Zone Answer Key provides answers to the activity sheet as well as additional points for discussion.

Questions for Students
 
In what ways is mathematics used in landscaping? What mathematics is involved when creating defensible space?
[Measuring distances, estimating areas, determining slope, and using proportions are all critical skills when creating defensible space.]

What are some effective strategies for estimating the area of defensible space zones?

[The area of each zone can be compared to a known area, such as the area of the house. Or, the area can be approximated using common shapes such as rectangles and circles.]

In addition to landscaping, where else might the Percent Slope tool be used?

[It could be used to find the percent slope of driveways, roofs, stairs, and other structures that involve angles.]

Assessment Options
 
  1. Ask students to write a description of how to determine proportional relationships and how to use visualization to make measurement estimates.

  2. As a class, review student answers to the In The Zone activity sheet. In the discussion, include what it means to "live with fire" and what new information about fire they have learned. Review the key questions to assess student understanding of the content of this lesson.

  3. Choose an irregular shape in the classroom, and allow students to estimate its area.

Extensions
 
  1. Have students respond to the following question:
    Some firefighters recommend that a fourth zone be used when creating defensible space. Zone 4 is the area 100’ to 200’ from the house. How would the area of this zone compare to the area of Zones 1, 2, and 3?

    Allow students to estimate the area of Zone 4 for the house shown on the In The Zone activity sheet. [Students should find that the area of Zone 4 is roughly equal to three times the combined area from Zones 1, 2, and 3.]

  2. Ask students to determine the amount it would cost to landscape the property, if the cost for landscaping differs between zones. For instance, the cost of landscaping close to the house in Zone 1 might be $20 per square foot, whereas it might only cost $5 to landscape one square foot of area in Zone 3.

Teacher Reflection
 
  • What additional examples do students need to model the size of objects using benchmarks? What experiences could help students recognize the absolute need for a referent in estimation activities?
  • What caused students’ confusion as they worked with proportional activities? What learning activities would help them understand proportional relationships?
  • Which students need more practice estimating the area of irregular shapes? What experiences would help them develop this knowledge and the associated skills?

NCTM Standards and Expectations
 
Geometry 6-8
  1. Understand relationships among the angles, side lengths, perimeters, areas, and volumes of similar objects.
  2. Draw geometric objects with specified properties, such as side lengths or angle measures.
  3. Recognize and apply geometric ideas and relationships in areas outside the mathematics classroom, such as art, science, and everyday life.
  
1 period   

NCTM Resources

Navigating through Geometry in 6‑8

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