Each EarlyLearny development set uses a different theme that is prepared according to the developmental ability and perception level of babies and children. The activities and instructions within the activity books are structured using these themes., , The subject matter of the EarlyLearny 21st month set is vehicles which have always been the center of curiosity for children because their size and the different sounds they make. The activities within the book will support the child's intellectual development. In addition, the child will learn the important habit of self-play and problem solving, sharing, learning limits, and the skills of learning and applying the rules.