Learning Scenario - Simple Sick (NetLogo)

Basic Model

Description

This is a very basic model that begins with a population of 199 healthy people and one sick person. When the sick person touches a healthy person they immediately become sick as well. This model shows how drastic situations can be due to the spread of disease. There are no parameters that can be manipulated in the model.

Background Information

This model shows the spread of diseases that eventually turns into an epidemic because of how large the population is. Just like in real life when a disease that starts to affect more than a few people in one area like a city then it becomes an epidemic. For example, the swine flu, the regular flu, and meningitis all started out small but then spread to many people and affected people from other cities and states. In reality, people are healed or become better as time goes on. This model shows what would happen if they did not.

Science/Math

Sick = Sick person + Healthy person. In this model there is no chance of a person getting sick. It is certain. This model shows interaction among species because it is the interaction between sick people and healthy people.

Teaching Strategies

First, have a discussion with students about various diseases and what is an epidemic. Examples to show what an epidemic is would be the flu, swine flu and, more historically, the Black Death. Next, have the students open the model and run the model. The model should be run at medium speed to show how easily a disease can spread. Have the students discuss what they see and how realistic or unrealistic the model is.

Implementation

How to use the model

This model is very simple in the fact it only has 4 components: the setup/run buttons, the sick/healthy person counter, the graph that charts the amount of sick and healthy people, and the environment. To start the program, click "set up model"; this will put 200 people in the environment. 199 will be healthy and one will be sick. Next, click "run model" to start the model and spread disease. To slow the model down to observe changes, drag the ball to the left away from "normal speed". If the program needs to be paused, click the run button again.

Learning Objectives

1. Understand how diseases spread

Objective 1

Through watching the model, students are able to see what an untreated disease outbreak looks like. Have the students run the model using various speeds. Ask the following questions:

1. How easily are diseases spread?
2. What types of diseases could the sick people have?
3. Is the model realistic?

Extensions and Related Models

1. Add in a recovery rate
2. Add in doctors and medicine

Extension 1

In reality, most people are usually able to recover after a while of being sick. This extension would be causing the sick to become well again after a while. Then, since they have gotten over the sickness they will become immune.

1. Will this affect the spread of disease?
2. What will be the ending result after a long period of time?

Extension 2

Doctors help to cure people when they become sick. In the model another agent would be added in to be a doctor. They would cure any sick person they come into contact with.

1. Will this make the model more realistic?
2. What will be the end result?
3. Will the disease spread faster or slower?

Related Models

Directable Fire!

This is an applet where the user starts a fire in one tree and sees how it affects the other trees. There is the option of resizing the forest, manipulating the burn speed and manipulating the probability of the trees around the tree on fire to burn.

Epidemic

This is an agent-based model that displays a very simple epidemic model. The only parameters are the amount of people and the infectiousness of sick people. Also the only types of people are healthy, sick, and immune.