Students investigate different ways that people become immune to pathogens.

After introducing the concepts of active and passive immunity, students explore one example of each in more detail. The active immunity activities focus on vaccination and the different ways that vaccines are made. Passive immunity activities focus on herd immunity, including use of a computer model that simulates herd immunity. Students use statistics and graphs to analyze data and compare how different immunization rates confer varying degrees of protection on vaccinated and unvaccinated populations.