Bug Hunt Predators and Invasive Species (NetLogo Model)

Novak, M. and Wilensky, U., Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
Type Category
Instructional Materials
Interactive Simulation , Simulation
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



This NetLogo simulation, developed at Northwestern University, models three initial populations (grass, bugs, birds) within an ecosystem over time. Settings within the simulation help students to make sense of how disruptions, such as an invasive species (mice), disease (reduction in number of bugs), and fire (burning of grass), may impact population dynamics and ecosystem stability over time. By manipulating these settings, students can ask questions and then look for evidence using mathematical representation to support their thinking about what factors affect biodiversity and cause populations to be either stable or unstable over time. Instructional supports include background information, instructions for using the simulation, and suggestions for extending the simulation. Although the downloaded version is recommended by the creators, a web version is also available at http://bit.ly/NetLogoSimulation.

Intended Audience

Educator and learner
Educational Level
  • High School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-LS2-2 Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

Clarification Statement: Examples of mathematical representations include finding the average, determining trends, and using graphical comparisons of multiple sets of data.

Assessment Boundary: Assessment is limited to provided data.

This resource was not designed to build towards this performance expectation, but can be used to build towards it using the suggestions provided below.

Comments about Including the Performance Expectation
Students engage in three-dimensional learning by manipulating values for factors that may impact the stability of different populations within a model ecosystem. When the simulation is run, a graph of each population’s size over time is shown. The initial populations’ sizes may be set, allowing students to see the impact of different scales. If “off” is selected for the “constant-simulation-length?” switch, the simulation will run indefinitely. In this case, the populations may get significantly larger and offer more opportunities to compare the model at different orders of scale. Students may then select additional constraints, such as the number of invaders, the amount of energy each invader consumes, the percentage of grassland burned by fire, and the percentage of bugs killed by disease. Teachers should allow students to first familiarize themselves with the instructions and the simulation. Selecting the “Info” tab at the top of the simulation will provide students with essential information about how to use the simulation as well as what each slider parameter represents. Once students are comfortable with using the simulation, one suggestion is for students to ask a specific question, make a prediction based on their question, and then design and execute an experiment that will provide evidence to either support or refute their prediction. Additional opportunities to support and defend their explanations with peers would increase the engagement and learning of this exercise.

Science and Engineering Practices

This resource was not designed to build towards this science and engineering practice, but can be used to build towards it using the suggestions provided below.

Comments about Including the Science and Engineering Practice
Each place in this activity where students make decisions about settings within the simulation are natural places for peer discussion, review, and defense. Teachers may want to provide students with opportunities to construct explanations as well as to review and revise their explanations; extensions of individual responses could include working as teams or sharing thoughts in other ways with their peers, using strategies such as “Think, Pair, Share” or poster sessions with peer reviews. Making their thinking explicit and sharing their thinking with others will help to deepen their understanding and their engagement. Taking snapshots of their graphs at the end of each run and including these graphs in their results will help to anchor their understanding of biodiversity and the factors that affect stability of populations.

Disciplinary Core Ideas

This resource was not designed to build towards this disciplinary core idea, but can be used to build towards it using the suggestions provided below.

Comments about Including the Disciplinary Core Idea
If students manipulate the different settings within the simulation to see how they can achieve stability within this model ecosystem, they will gain an understanding of how these factors impact biodiversity and ecosystem stability. The introduction of mice represents an invasive species, and students may want to explore the different ways that such a species can disrupt a local ecosystem and/or whether the ecosystem can return to the original status. Disease and fire are the other two disruptions that students can manipulate. Examples of ecosystem function, biodiversity, and responses to disturbances from their own geographic area may help to relate this simulation model to the real world.

Crosscutting Concepts

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
The simulation provides an opportunity for students to compare populations of different scales by changing the initial settings of the sizes of the populations and by letting the simulation run for longer periods of time. Encourage discussion among students about how each of the three possible disturbances affect populations of different sizes. Explore the significance of the differences in scale. Other crosscutting concepts that are supported with the simulation and which could be extended are cause and effect and stability and change. Students can use the population size graph as evidence of what happens over time (effect) to the different populations when a particular variable is changed (cause). Stability can be reflected by a population size not showing significant change over time.

Resource Quality

  • Alignment to the Dimensions of the NGSS: Students engage in three-dimensional learning by using the simulation as a model to create evidence to support explanations about how different factors may affect biodiversity and ecosystem function at different scales. Teachers will need to facilitate and guide students’ use of the simulation so that each run of the simulation serves this purpose. Taking screen snapshots of the population curves over time will help to support student explanations. Students should be cautioned to design a controlled investigation by changing only one parameter at a time so they can be sure of the cause of each effect they record. Students should also be encouraged to try the same change with a small and a large population to see the effect of scale. Taking time to stop and share results will help students to make sense of these phenomena.

  • Instructional Supports: This simulation is a type of model, so teachers may want to present and discuss authentic examples of stable and unstable natural populations familiar to the students prior to doing the simulation. After completing the simulation, teachers may then want to connect back to these introductory examples. In doing so, students will be supported in connecting the learning from the simulation back to real, authentic examples. The instructions provide suggestions for how to use the simulation, as well as suggested extensions. Suggestions for differentiated learning are not contained within the simulation. A user manual for the simulation may be found by selecting “Tutorial #1 Models” at: http://ccl.northwestern.edu/netlogo/docs/.

  • Monitoring Student Progress: Although there are no formal formative assessments designed within this simulation, the simulation itself elicits direct, observable evidence of three-dimensional learning; students are using mathematical practices to make sense of biodiversity and the factors that ecosystem resilience while changing the settings to consider populations at different scales. Suggestions are made to help guide the instruction along paths that promote learning. Students have multiple ways to design their own experiments so that teachers can assess their understanding of the phenomenon. Screen snapshots may be taken of the simulation and explanations of the snapshots/graphs can provide an artifact for formative assessment.

  • Quality of Technological Interactivity: This simulation rates high in technological interactivity. It is recommended that you download the NetLogo program first. The “Bug Hunt Predators and Invasive Species” model is included in the Models Library (Under “File” at the top of the simulation) under the subheadings “Curricular Models,” and then “BEAGLE Evolution”. The simulation may also be run using the web version available at http://bit.ly/NetLogoSimulation. If a teacher or student knows how to code, the simulation may be modified and shared with a broader community of NetLogo users.