In the United States, the average age for a girl to get her first period is 12. This does not mean that all girls start at the same age. A girl can start her period anytime between the ages of 8 and 15. Most of the time, the first period starts about 2 years after breasts first start to develop. If a girl has not had her first period by age 15, or if it has been more than 2 to 3 years since breast growth started, she should see a doctor.
Cancel Save! You can build a balance beam out long pieces of wood covered with thick cloth, or sand it smooth so you don't get a splinter. A piece of wood laid on the ground is not a balance beam. Balance beams are 10 cm wide, 500 cm long, and usually 124 cm off the ground. Post Your Project.
1 A regulation balance beam measures 16.5 feet (5.02 m) long by 4 inches (10.2 cm) wide and sits 4 feet (1.2 m) off the floor.