If you push pre-schoolers too much with their learning they may resist. If you give them too much room they will look for something more interesting to do. A key challenge for nurseries and parents/carers is to help them find something interesting with just enough information to spur their curiosity, but not so much that the subject becomes boring.
Children who know less about situations and outcomes often want to learn more; the idea being that a knowledge gap can be deeply motivating. Curiosity-driven learning can happen both in structured learning environments like nursery, as well as in home settings.
One option is to ask children open-ended questions, essentially exploiting their knowledge gap and the motivation this gap generates. Try it! It can provide an endless supply of entertainment!
Reading to pre-schoolers is also a highly beneficial activity which can be supported by open-ended questions. Nurseries and parents/carers need to judge when to provide a complete answer to a pre-schooler and when to let them struggle through the process of exploration.