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Choose an initial number of bugs, invaders, and birds to include in each environment. Make each at least 5.
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Set the initial values for the amount of food bugs eat, the amount of food invaders eat, and the region amount of grassland to different combinations you decide. If you want to test the effect of changing one variable between the ecosystems, remember to make the other variables the same in both ecosystems.
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Press SETUP and then press GO/STOP. As the model is running, press the LAUNCH AN INVASION button, sometime between a time of 100 and 500 .
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Run the model until it pauses on its own.
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Record your observations below. Try getting the two outcomes you selected by trying different combinations of values. If you can't find at least one set of values for each of the two outcomes you selected, then test some new possible combinations of values if time permits.
Design Your Investigation
Pick two of the following outcomes to generate in the model:
Outcome A: All three populations (bugs, invaders, and birds) die off.
Outcome B: The predator population dies off, but bugs or invaders survive.
Outcome C: The average predator population is above 100.
Try to find solutions that work consistently. If you run the model several times with your parameters, your chosen outcome should happen most of the time.
