1) The largest known dinosaur, Argentinosaurus, weighed around 70-100 tons and measured up to 100 feet in length.

2) The word "school" contains two vowels: O and O.

3) The first successful human heart transplant was performed by Dr. Christiaan Barnard in 1967.

4) The Cuban Missile Crisis in 1962 brought the United States and the Soviet Union to the brink of nuclear war during the Cold War.