In this activity, students will design and run experiments to see if adding a predator has an impact on the ecosystem. This activity will reinforce the concepts of energy flow through ecosystems and the often unexpected results of interactions in complex adaptive systems. The “Experimental Design” form will be used to describe and report out on the investigation. 

• Watch the video on setting up your experimental design
• Set up your experimental design
• Run your experiment
• Collect and analyze data
• Upload your experimental design form and a link to your model.

Video introduction of setting up your experimental design:

Set up your experimental design

• Use the Experimental Design form  and the Scientific Practices with Computer Modeling & Simulation form and guide students as they develop a scientific question in pairs. Emphasize the need to run repeated trials and to clearly identify the variables, as well as the difference between a question and a testable question.
• Determine and record which variable will you be changing, the range for that variable, and how many trials to conduct at each setting. This information should be written into your template documents before beginning. (See the Cookbook  for details on how to add a slider.)
  
• Determine how you will be collecting and analyzing data. Is there instrumentation you will be using to monitor and record the behavior of the system? How long will you continue to collect data? How will you look for patterns in your data? [Will you draw a graph and/or make a table to record your observations?] (See the Cookbook  for details on how to add a data box.)

Run your experiment

• Run your experiment in pairs so the question can be answered.
• Follow what you described in the Experimental Design form to determine which variable you will be changing, and how many trials you will make at that setting.
• After running the trials at each setting and recording the outcome data, move to the next setting in the range. Again, conduct these trials and record the outcome.
  

Collect and analyze data

• Compare the data you collected. Do you notice a trend?
• Graph your data points. Do you notice any trend? What can you say now about your testable idea?
• Share out your experiment and results with the class.
• Discuss the difference between correlation and causation.

Reflection:

Upload your experimental design form and the link to your model to your portfolio in the section "SL Nova Projects- Life" under the heading "Adding a Predator".