1) The first computer mouse was invented by Douglas Engelbart in 1964 and consisted of a wooden shell and two metal wheels.

2) The Dow Jones Industrial Average (DJIA) is a stock market index that tracks the performance of 30 large, publicly owned companies in the United States.

3) The word "bank" comes from the Italian word "banco," which means bench. In medieval Italy, bankers conducted their business on benches in the marketplace.

4) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.