Lots of kids go through times when they'd like to change their hair. Often, it's girls who are most concerned , but boys may be interested in how their hair looks, too. Sometimes hair will change as you get older----all by itself----when you go through puberty . Maybe it used to be lighter and now it's darker. Or maybe it's oilier than it used to be, and now you need to wash it more. It's also normal, as you're getting older, to notice your appearance more often. You might suddenly decide you want a hairstyle like other kids at school have. But some styles and looks require chemical treatments and long hours in the chair at the hair salon. Some people dye their hair a different color, get a bunch of braids ,or make their hair straight when it's curly . Are these treatments OK for kids? That's something you should discuss with your parents. At any age, any chemical or heat applied to  the hair can damage the hair or cause it to break off. Any styling that pulls hard on the hair can also hurt the scalp  or cause hair loss. Styling tools, such as curling irons and straightening irons, get very hot and can cause burns. And chemicals used to color, curl, or straighten hair can be very harmful if they get into your eyes or onto your skin. Which of the following is NOT the cause of changes of one's hair mentioned in the passage?
Change the hair style to act in a play. It changes naturally with the age. You want to make yourself look beautiful or cool. A boy's hair may become darker and darker when he gets older.