Forest Fire!

In this activity you will use a Java model called "Fire!!" This model simulates a forest with trees in a square grid. The forest has 17 trees on a side.

How many trees are there in this simulated forest?

Models use assumptions. The real world is very complicated. Any situation like a forest has hundreds of factors and a wide range of variation for each of the factors.

For example, most forests have many different kinds of trees. Even in forests that are planted with only one kind of tree, some of the trees are taller than others. One tree may have grass growing under it, a second may have berries, and a third may have rocks under it.

If you spent time observing a section of forest, you could find hundreds of factors that could affect how a fire would spread. This poses two problems in constructing a model of the forest.

1. Scientists haven't had time or resources to measure the effect of these factors on the spread of a fire. Without good measurements, we don't know how to accurately account for each factor in our model.

2. The more we include in our simulation, the harder it is to write the model and the slower the model runs. For example, scientists can use the best super computer to accurately predict if it will rain on your school or house tomorrow. Unfortunately, it would take that super computer 24 hours to do all of the calculations. If you have to wait 24 hours, it is easier and cheaper to just wait and look out the window.

Because of these kinds of problems, scientists can either find an exact answer to an approximation of a situation or find an approximate answer to an exact situation.

When scientists develop models, they make assumptions to simplify or approximate the situation. The scientists know that the assumptions aren't exactly true. The simplified model allows the scientists to understand a simple approximation of the forest. Later, if time allows, the scientists can add more factors to the model to more closely simulate the real situation.

This model makes the following assumptions:
1. All of the trees are identical and are an equal distance from their neighbors.
2. Every tree has an identical chance of catching fire if its neighbor is burning.
3. Either there is no underbrush or this additional fuel affects all of the trees the same.
4. There is no wind to push the fire in any direction.
5. There are no hills, valleys, or water that would effect how the fire would spread.

1. background

3. how