1) The Arctic Ocean is the smallest and shallowest ocean, located at the North Pole. It is covered by sea ice for much of the year.

2) The Industrial Revolution led to significant urbanization, as people migrated from rural areas to cities in search of employment in factories.

3) The legislative branch in many democracies is responsible for making laws, representing the interests of the people, and providing checks and balances on the executive branch.

4) The world's largest desert is the Sahara Desert in Africa, covering an area of about 3.6 million square miles (9.4 million square kilometers).