 Preview - Evolution Of Populations

## Systematically investigating the spread of a forest fire

Let's investigate how the density of the trees affects the spread of a forest fire. We will first generate some data using the Fire model and then visualize that data using another computational tool called CODAP.

Follow the experimental design that is described below:

Research Question: How does the density of trees in a forest affect the spread of a forest fire?

Hypothesis: As the density of trees in the forest increases, the percentage of forest burned will increase "linearly". (That means, if density of trees doubles, the percentage of forest burned will also double)

Let's test our hypothesis using the model.

Change the values of density systematically (plan out a series of different values to try). Record the value of 'percentage burned' in the data table for each density. Make sure that you press the 'setup' button every time you do a trial. Make sure to run each different value of density twice (2 trials) and finally, make sure you record values for each experimental trial.

CODAP will automatically graph the average of the two trials that you will record.

### Questions

Write some observations about the graph of 'density%' vs 'percent burned average'.

Do you think that the evidence that we gathered with our experiment supports our hypothesis?

The spread of a forest fire is an emergent phenomenon. Below a certain density, the fire does not spread much, however when the density crosses a 'tipping point' or threshold, the fire engulfs almost the whole forest.

The tipping point in this model falls within which of the following density ranges?

Between 30 and 40
Between 40 and 50
Between 50 and 60
Between 60 and 70

Can you give an example of another phenomenon with a tipping point?

### Notes

These notes will appear on every page in this lesson so feel free to put anything here you'd like to keep track of.