Children

http://www.guardian.co.uk/stage/theatreblog/2009/jan/07/theatre

Interesting... Especially for you currently studying or recently graduated. Because so often Drama Students are asked to play much older than themselves. This presents a whole set of other problems.

And this can lead to 'blinding' ourselves into thinking "Well, Im young, so I can play younger a lot better than I can play older!". But there is still incredible craft, detail and respect needed to play a younger character. After all, everybody in your audience has been young, but not everybody has been older. So they are more highly tuned to the subtleties present in a younger character.