Justin Gatlin hands his son, Jace, a flag after winning the men’s 100-meter dash in the U.S. Olympic Trials in Eugene, Oregon. (ROBERT GALBRAITH/REUTERS)

The Fourth (of July, that is) means a time for flags and fireworks. You’ll be seeing lots of both this week. (The Fourth of July, also known as Independence Day, is Wednesday.) Fireworks come and go, but the flag stays around all year long, for more than 236 years.

All of which got us thinking about the flag and how little we know about its history and symbolism. So here are a few of the fascinating facts we discovered when we did a little research. You can share them with your friends and family while you’re waiting for fireworks to go KA-BOOM on Wednesday.

The first flag was adopted on December 3, 1775. It was the only flag in U.S. history to have no stars. (It had 13 stripes and a field of crossed bars where the stars are now.)

The flag once had 15 stripes. (The star-spangled banner that flew over Fort McHenry and inspired the national anthem was a 15-stripe flag). In 1818, Congress adopted a plan that the number of stars should reflect the number of states and that the number of stripes should go back to 13 to honor the original colonies.

The flag’s design has been changed 26 times. The stars have been arranged in patterns including rows, circles and even stars!

The 50-star, 13-stripe flag has been in use since July 4, 1960, making it the longest version in use.

The current version of the flag was designed as a school project by 17-year-old Robert G. Heft. He got a B- for his design. His teacher changed his grade when Congress decided to use his flag.

●Six U.S. flags have been raised on the moon.

● There are some places where the flag must be flown continuously. They include:

■ Fort McHenry in Baltimore.

■ Marine Corps War Memorial in Arlington (also known as the Iwo Jima Memorial).

■ The White House.

— Tracy Grant