单项选择题

Changes have come into museums. They are not places that one "should" go any longer but a place to get pleasure.
If you go to a science museum in Canada, when harmless electricity passes through your body you can feel your hair stand on end. At the Children’s Museum in New York, you can strike an African drum. In some other museums in the USA, "Do Not Touch" signs do not exist.
It is realized by more and more museum directors that when becoming a part of what they are seeing, people get the best learning effect. Many science museums encourage visitors to touch, listen, operate as well as experiment in order that they can discover scientific rules by themselves.
The intention of the change is not only to provide pleasure, but make people feel easy in the scientific world. Suppose you don’t understand science, you will fear it; and when you fear science, you may not make the best use of it.
The rise in wealth and spare time is one of the reasons for all these changes. Another reason is the increasing number of young people in the whole population. Among them are mainly college students or college graduates, with a new and totally different way of seeing the world. They want art which they can take part in. It’s also true in science and history.
Ancient museums have been changing and the government is encouraging to build new, modern museums. There are more than 6,000 museums in the United States and Canada, which are almost twice as it was 25 years ago.

The main idea of this text is to（）

点击查看答案&解析