Help! My Class is on Fire
An introduction to Simulations
Teachers Notes:
This is a simple
interactive introduction to simulations in which the students play the agents
(trees) of the simulation of a forest fire.
A Java applet for simulation of a forest fire that may be used with this
introduction can be found at The Shodor web site at http://www.shodor.org/interactivate/activities/fire2/
.
Setup: Students
should be arranged in desks or chairs that are rectangular. It is not necessary that every desk is
occupied, and may actually work better if they are NOT all occupied. Number the rows of desks (chairs) from left
to right, and a second value from front to back. Obtain a randomizing device
that will allow you to determine an initial seat location at random; Subsets of
a deck of cards (red for rows and black for columns for example) or numbers
written on pieces of paper drawn from a hat are possible examples. Students
need a coin, spinner, or other device to randomize their decisions.
Explain to the students that they are trees
in a forest. Students sitting are green
trees. Standing students represent a burning tree. When they burn out they move
to the ash pile to be counted (front or side area of the room).
Instructions:
1)
All students
begin sitting, and a random location is selected for a “lightning strike”. The student in that location catches fire
(stands up).(see options for step 1 below)
2)
On each
successive round the following three actions are performed:
a. Any tree that has a burning tree in the chair
in front, back, left or right of them catches fire (see options for step 2a
below)
b. Any tree that was standing when the round
began burns out and moves to the ash pile (see options for step 2b below)
3)
Steps 2a and 2b
are repeated until the forest is burned completely, or the fire goes out (no
one is standing).
4)
The percentage
of the forest consumed (number in ash pile divided by total number of students)
is recorded. Several repetitions of the
same game should be done to illustrate that with the same initial conditions,
chance events can lead to very different results.
5)
Some teachers
may wish to use the Shodor Fire applet at this point to allow students to
replicate more fires and collect and display data. Note that students can alter wind direction, wind speed and
forest density in the model. [It would
be good to have students discuss how they might alter their physical simulation
to account for these two factors]
Options: Below are some simple options for modifying the simulation. Students should be encouraged to discuss the characteristics that impact forest fires spread, and how they could implement these factors in their physical model.
Options for 1. Start multiple random locations on fire;
Start
an entire row on fire
Options for 2a.
Students
may use a randomizing device to determine if they catch fire. For example, each student may use the logic
(If an adjacent tree is on fire and I flip HEADS [or roll a number less than
3 on one die, etc..] then I catch fire).
Students could count the trees on the diagonal to their chair as “next to”.
Students may be randomly assigned at the beginning to be two different types of trees (pine and oak) with different probabilities of burning.
Options for 2b. Trees may burn for longer periods of time before they burn out.
Trees may use a randomizing device to see if they burn out or not (heads I burn out, tails I keep burning).
Other options: Encourage students to suggest other factors that might influence the spread of forest fires, and how they might implement these factors in their model. Ask students to discuss other physical events that might be modeled in a similar manner.