Watch this UNICEF video about polio on HowStuffWorks. School projects in Nigeria are trying to reach more than 14 million children; the concept involves a homework assignment where each student has to find and bring 10 children to get vaccinated. Nigeria has about 1,200 polio cases which represents more than 50% of the reported cases worldwide; Nigeria is one of four countries in the world where polio is still an epidemic. See how polio vaccines and immunizations work in this video from UNICEF.