1) The blue whale is the largest animal to have ever existed, with an average length of about 82 feet (25 meters).

2) The Industrial Revolution, which began in the 18th century, brought about significant changes in agriculture, manufacturing, mining, and transportation.

3) The world's largest flower is the Rafflesia arnoldii, which can grow up to 3 feet (1 meter) in diameter and weighs about 15 pounds (7 kilograms).

4) Lightning strikes the Earth about 8 million times a day.