Adding a line graph
• We need some way of tracking the spread of disease; what data should
we collect?
• What do you want to find out using the model? [Does everyone get sick?
If so, how fast? For example, if we are interested in seeing how fast the
disease spreads, we will need to know when everyone is sick.]
• If we want to know if anyone remained healthy throughout the epidemic,
we need to keep track of the number of healthy people.
• Let’s create a new line graph called “Population Healthy and Sick”
• How can we track the sick and healthy people? What is different about
how they are displayed? [healthy are blue and sick are red]
• Demonstrate how to create a line graph using the slide presentation or
StarLogo Nova.
• In the Colliding Turtles model, turtles always reacted to a collision. In our
epidemic model, we will incorporate a transmission rate so only some of
the time a disease is passed from one agent to another.
• Demonstrate how to create a widget (page 73) or show students using
the power point presentation
http://www.projectguts.org/resources
• Drag the line graph off to the side of Spaceland but still inside the
browser window.
• Double click on New Series and change its name to “Count Healthy”
then select blue as its line color.
• Add another Series and change its name to “Count Sick” then select red
as its line color.
• Finally, click “Edit Widgets” to leave editing mode and return to play
mode.
• Next, we want “The World” to update the line graph each time through
the forever loop, so we need to add a while forever toggled command
to the page labeled “The World.”
• Notice that we need the “clock” along the x-axis and the count of blue
turtles on the y-axis. We can get the count of turtles that are blue using
the count command. Since the whole Spaceland is less than 150 steps
square, saying “within 150 steps” will get us the number of turtles that fit
this criterion across all of Spaceland.
• Add 2 new blocks to your Setup procedure- clear line graph and set
clock (to 0).
• We recommend that you save and refresh the browser window.
• If the graph and other widgets disappear, try resizing the browser
window by grabbing a lower corner to make it bigger and smaller.
The widgets will likely reappear.