For 3-year-olds
At three, a child can hold the shape of a whole day in mind, so the questions get bigger: what happens in between, who will be there, will anyone play with me. Stories with a clear beginning, middle and end help here, especially ones that follow a character through arriving, finding something to do, and being collected again. Some worry or a wobbly moment is useful at this age, as long as it settles. This is also when the social side starts to matter, so a story that includes joining a group or making a first friend gives your child something to try out.