1) The world's oldest known recipe is for beer and is over 4,000 years old.

2) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

3) The role of the judiciary is to interpret laws, resolve disputes, and ensure justice in accordance with legal principles and the constitution. It serves as a check on the executive and legislative branches of government.

4) The invention of the printing press by Johannes Gutenberg in the 15th century revolutionized the spread of knowledge and played a key role in the Renaissance.