A hydraulophone is a musical instrument played via direct physical contact with a hydraulic fluid, typically water. The sound is generated from the vibration of the instrument’s liquid and changes based on the position of the fingers in relation to the finger holes. The invention of such devices led to the creation of a physics-based classification system for instruments that takes into account the state of matter that initially produces their sound. What are the five categories of this system? Discuss
Source: The Free Dictionary
Thank goodness…I was never sent to school…it would have rubbed off some of the originality. 
Emperor Gaozu was the founder of the greatest of China’s imperial dynasties, the Tang dynasty (618-907 CE), which ruled over what was then the world’s largest empire and initiated a golden age for art, science, and Buddhism. Before becoming emperor, Li Yuan, as he was then known, was governor of a province under the Sui Dynasty. When the Sui emperor, Yangdi, was assassinated in 618, Li Yuan reunited the empire and took power. Why did he later abdicate the throne in favor of his son, Li Shimin? 
Lou Bunch Day is an annual reminder of the rowdy gold-mining days of 
Mallory was an English mountain climber who participated in the Everest expeditions of 1921, 1922, and 1924. The 1924 expedition culminated in a bold and possibly successful drive toward the summit by Mallory and Andrew Irvine, from which they did not return. Mallory’s body was discovered on Everest in 1999. His achievements and the mystery surrounding his final effort have made him a mountaineering legend. What “three most famous words in mountaineering” are attributed to Mallory? 
Strange animal behavior, changes in electromagnetic fields and the hydrogen content of soil, and the appearance of unusual clouds have all been cited as phenomena potentially related to impending earthquakes, yet earthquake prediction remains a controversial field. Skeptics maintain that there is little evidence linking observable factors with subsequent earthquake activity. What are the arguments against alerting people in advance if there is a chance of an earthquake?