In this sentence the article (das Mädchen is singular, die Mädchen is plural). Other sentences, context or verb conjugation.

Hope that helps!

Yeah Mädchen as singular is a neutral noun, and as I've just learned, so are all nouns ending with -chen and -lein. Though die is used for feminine nouns like Frau, it is also used for plurals regardless of the subject's gender.

By plural you have every time DIE Mädchen, that is the only diference