You will select 3 variables to change in the code. Before changing a variable, setup the model how you will run it each time, then run it to 100,000 ticks and record observation. Change value of the variable in the code. Predict how the new value will affect the model. Run model to 100,000 ticks and record observation. Change variable back and pick a new one. Values you can change:
initial temperature
heading of a turtle
random numbers (eg. random 50, generates random numbers from 0 to 50)