Buffy Pier, age 11, of Lansing, Mich., for her question:

WHO INVENTED ROLLER SKATES?

It is estimated that more than 20 million Americans enjoy roller skating. There are more than 4,000 roller rinks in the United States and Canada.

We aren't sure exactly who invented roller skating.

But a man named Joseph Merlin was one of the first to demonstrate skates which he invented. He came up with his set of wheels in London in 1760.

By the mid 1800s roller skating had become very popular in England. Indoor rinks were established in London and other large British cities.

An American named James Plimpton invented an improved skate in 1863.

Most of today's skating rinks have floors that are covered with a thin layer of plastic which is replaced every few months. The coating keeps the skate wheels from slipping.