Play people are an especially important part of any pre-school toy box. In these characters children recognise themselves and their families and friends. Their play is usually about enacting real-life or imagined scenes - simple scenarios such as being at home in the kitchen or driving along in the car - compounding their understanding of the world and how everyone in it plays a part. Pre-schoolers are particularly interested in exploring the boundary between good and evil and it is for this reason that 'superhero' play is so popular at this age.
If you have boys and are concerned that they play exclusively with trains or dinosaurs and spend their days choo-chooing or roaring, try adding a few figures to their play. Adding a train driver or passengers to a train set encourages dialogue between characters and makes the child more likely to 'narrate' the action, both fantastic ways to promote language development.