When children first enter, they have to type in their school, class, name, and other personal information, so I think it's a parental decision whether or not you let children take part in the project. There is a video and characters have accompanying ㄅㄆㄇㄈ, so elementary students should be able to navigate their way around the site.
If you want to participate, you have to do so before November 15, 2011.