Ask unlimited questions for free
Asthma is the most common chronic childhood disease in the world. Most children who develop asthma have symptoms before they are 5 years old.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
Earwax has antimicrobial properties that reduce the viability of bacteria and fungus in the human ear.
For a complete list of videos, visit our video library