1) The Amazon rainforest produces more than 20% of the world's oxygen.

2) The world's largest ocean, the Pacific Ocean, covers an area of approximately 63 million square miles.

3) The windshield wipers were invented by a woman named Mary Anderson in 1903.

4) International relations encompass the study of relationships between nations, including diplomacy, treaties, and foreign policy. It examines the interactions and dynamics among different countries in the global arena.