NetLogo_Wolf Sheep Predation Model

Uri Wilensky
Type Category
Instructional Materials
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 by Uri Wilensky at Northwestern University, models three populations (wolf, sheep, grass) within an ecosystem over time. Settings within the simulation help students to make sense of the phenomenon of carrying capacity by allowing them to mimic changes in initial population sizes, reproduction rates, and energy gain from food. By manipulating these settings, students can ask questions and then look for evidence to support their thinking about what factors affect carrying capacity 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. In addition, two papers written by Wilensky are referenced. One is available online at:

Intended Audience

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-LS2-1 Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales

Clarification Statement: Emphasis is on quantitative analysis and comparison of the relationships among interdependent factors including boundaries, resources, climate, and competition. Examples of mathematical comparisons could include graphs, charts, histograms, and population changes gathered from simulations or historical data sets.

Assessment Boundary: Assessment does not include deriving mathematical equations to make comparisons.

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 three different factors that impact the stability of three different populations within an ecosystem. When the simulation is run, a graph of each population over time is shown. The size of the initial population may be set, allowing students to see the impact of different scales. Teachers may want to allow students to first familiarize themselves with the instructions and the simulation. Once students are comfortable with using the simulation, one suggestion is for students to ask a specific question, develop a hypothesis based on their question, and then design and execute an experiment that will provide evidence to either support or refute their hypothesis. 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 would include working as teams or sharing their thoughts in other ways with their peers. 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 the phenomenon of carrying capacity and the factors that affect it.

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
Peer discussion/explanation/defense of ideas about limiting factors of all three populations are all natural extensions of this activity. 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 carrying capacity.

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. Encourage discussion among students about how populations of different sizes compare. 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.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This simulation supports three-dimensional learning by engaging students in mathematical thinking as they explore factors that affect carrying capacities of different populations at different scales.

  • Instructional Supports: Because this simulation is a type of model, 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 itself, but the paper accompanying the simulation, referenced in the simulation description, contains ideas for how to engage students and guide their inquiry. A user manual for the simulation may be found by selecting “Tutorial #1 Models” at: .

  • 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 carrying capacity and the factors that limit population size 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 to provide an artifact for formative assessment.

  • Quality of Technological Interactivity: This simulation rates high in technological interactivity. If a teacher or student know how to code, the simulation may be modified and shared with a broader community of NetLogo users. It is recommended that you download the NetLogo program first. The Wolf-Sheep-Predation model is included in the library within the downloaded application. It is NOT recommended that the model be run in a web browser.