Puzzles
Puzzles can entertain a preschooler as well as develop his problem solving abilities. Puzzles involve strategy and require concentration, something that is difficult for a preschooler, so it's a challenge. Choose simple puzzles with minimal pieces until the preschoolers are able to handle more complicated puzzles.
Puppets
Puppets encourage a preschooler to expand her imagination to tell stories and interact with other characters. Kids can play with puppets individually or as a group where they take turns using each puppet and interacting with the others. Preschoolers can also make their own puppets out of old socks or paper bags.
Blocks
Blocks are an educational toy because they work on developing coordination and fine motor skills. You should give preschoolers larger blocks (not small LEGO size) due to choking hazards. Let preschoolers build whatever sparks their imagination. Instruct preschoolers to use specific colors of blocks or create patterns.
Play Kitchen
A play kitchen teaches role play in which preschoolers can mimic their parents and caregivers. Fill the play kitchen with fake food and dishes so the preschoolers can pretend to cook and eat. Role playing helps develop a preschooler's imagination and understanding of the world around him.