Expansion set. With the help of more than 25 components that can be combined in various ways, preschool children can try out different designs and build entirely new buildings and places. With so many combinations, there is no wrong way to play. Where development comes into play: creativity and imagination. There are no limits to imagination when children creatively expand their Wonder Workers world. Planning and construction: Preschoolers develop their design skills and abilities as little builders by repeatedly constructing their structures and combining the building blocks into different creations.