At the Space Academy, we learn all about charts and how to use them. Some charts show how things change over time, like the speed of our space ship over the course of a journey.
Doctors use charts too. Your doctor will be looking at something called a 'growth chart'. These charts show the expected heights of boys and girls as they get older:
Your doctor will use a growth chart to see how your height compares with that usually seen in children of your age. If you are shorter than usual, your doctor can give you growth hormone treatment to help you grow taller. The growth chart is then used to keep track of your progress over time.