The following "Web lab" simulates the potential spread of HIV through
a population of 10 - 30 people. Each participant begins with a virtual
sample of body fluid. You will choose the number of HIV+ people
within the population. HIV status is assigned randomly by the computer.
You will not know who is initially HIV+. A sample of this original
fluid, before mixing, is archived by the computer. Each participant
will exchange fluid with another participant chosen at random by
the computer. The computer will generate three rounds of fluid exchanges
and display the results.
Following fluid exchanges, the computer simulates an ELISA (enzyme-linked
immunosorbent assay) to determine which fluid samples are now HIV+
and displays the results. Next the detective work begins. Knowing
the HIV status of all participants, you should be able to narrow
down the list to a few individuals who may have been the original
carriers. You can perform an ELISA on fluid archived before the
mixes to determine who was initially HIV+.
This activity is designed so that each browser session is unique (after 30 minutes of inactivity, the session is considered closed, and new data must be entered.) In other words, if a class of 20 students with individual computers each run the simulation, even with the same set of names, the outcomes will vary. This design prevents other users from overwriting your data in the middle of the simulation. The possibilities for classroom use are:
1. An instructor uses a single browser connected to an overhead projector. With class participation, names are selected and the simulation is run for all to see.
2. In a classroom with computer management software that allows an instructor to "push" their screen onto all the computers in the room, a single simulation is run on the instructor's computer and viewed simultaneously by all students on their individual or shared computers.
3. Each student runs their own copy of the activity in their browser. The specific results will vary, but overall the spread of HIV will be similar in all instances. This would allow using the activity as a self-directed experience by the students, who could then compare their results.
We welcome your comments and suggestions as to how we might improve this activity! Please use the Biology Project Contact form to share your ideas with us.